diff mbox series

[v2,6/9] KVM: arm64: Detect and handle hypervisor stack overflows

Message ID 20220222165212.2005066-7-kaleshsingh@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: Hypervisor stack enhancements | expand

Commit Message

Kalesh Singh Feb. 22, 2022, 4:51 p.m. UTC 
The hypervisor stacks (for both nVHE Hyp mode and nVHE protected mode)
are aligned to twice their size (PAGE_SIZE), meaning that any valid stack
address has PAGE_SHIFT bit as 0. This allows us to conveniently check for
overflow in the exception entry without corrupting any GPRs. We won't
recover from a stack overflow so panic the hypervisor.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
 arch/arm64/kvm/hyp/nvhe/host.S   | 16 ++++++++++++++++
 arch/arm64/kvm/hyp/nvhe/switch.c |  5 +++++
 2 files changed, 21 insertions(+)

Comments

kernel test robot Feb. 23, 2022, 2:04 a.m. UTC | #1 
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-defconfig (https://download.01.org/0day-ci/archive/20220223/202202230932.BKc5SFqd-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 11.2.0
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/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=gcc-11.2.0 make.cross 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@intel.com>

All warnings (new ones prefixed by >>):

   arch/arm64/kvm/hyp/nvhe/switch.c:197:43: warning: initialized field overwritten [-Woverride-init]
     197 |         [ESR_ELx_EC_CP15_32]            = kvm_hyp_handle_cp15_32,
         |                                           ^~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:197:43: note: (near initialization for 'hyp_exit_handlers[3]')
   arch/arm64/kvm/hyp/nvhe/switch.c:198:43: warning: initialized field overwritten [-Woverride-init]
     198 |         [ESR_ELx_EC_SYS64]              = kvm_hyp_handle_sysreg,
         |                                           ^~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:198:43: note: (near initialization for 'hyp_exit_handlers[24]')
   arch/arm64/kvm/hyp/nvhe/switch.c:199:43: warning: initialized field overwritten [-Woverride-init]
     199 |         [ESR_ELx_EC_SVE]                = kvm_hyp_handle_fpsimd,
         |                                           ^~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:199:43: note: (near initialization for 'hyp_exit_handlers[25]')
   arch/arm64/kvm/hyp/nvhe/switch.c:200:43: warning: initialized field overwritten [-Woverride-init]
     200 |         [ESR_ELx_EC_FP_ASIMD]           = kvm_hyp_handle_fpsimd,
         |                                           ^~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:200:43: note: (near initialization for 'hyp_exit_handlers[7]')
   arch/arm64/kvm/hyp/nvhe/switch.c:201:43: warning: initialized field overwritten [-Woverride-init]
     201 |         [ESR_ELx_EC_IABT_LOW]           = kvm_hyp_handle_iabt_low,
         |                                           ^~~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:201:43: note: (near initialization for 'hyp_exit_handlers[32]')
   arch/arm64/kvm/hyp/nvhe/switch.c:202:43: warning: initialized field overwritten [-Woverride-init]
     202 |         [ESR_ELx_EC_DABT_LOW]           = kvm_hyp_handle_dabt_low,
         |                                           ^~~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:202:43: note: (near initialization for 'hyp_exit_handlers[36]')
   arch/arm64/kvm/hyp/nvhe/switch.c:203:43: warning: initialized field overwritten [-Woverride-init]
     203 |         [ESR_ELx_EC_PAC]                = kvm_hyp_handle_ptrauth,
         |                                           ^~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:203:43: note: (near initialization for 'hyp_exit_handlers[9]')
   arch/arm64/kvm/hyp/nvhe/switch.c:208:43: warning: initialized field overwritten [-Woverride-init]
     208 |         [ESR_ELx_EC_SYS64]              = kvm_handle_pvm_sys64,
         |                                           ^~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:208:43: note: (near initialization for 'pvm_exit_handlers[24]')
   arch/arm64/kvm/hyp/nvhe/switch.c:209:43: warning: initialized field overwritten [-Woverride-init]
     209 |         [ESR_ELx_EC_SVE]                = kvm_handle_pvm_restricted,
         |                                           ^~~~~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:209:43: note: (near initialization for 'pvm_exit_handlers[25]')
   arch/arm64/kvm/hyp/nvhe/switch.c:210:43: warning: initialized field overwritten [-Woverride-init]
     210 |         [ESR_ELx_EC_FP_ASIMD]           = kvm_handle_pvm_fpsimd,
         |                                           ^~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:210:43: note: (near initialization for 'pvm_exit_handlers[7]')
   arch/arm64/kvm/hyp/nvhe/switch.c:211:43: warning: initialized field overwritten [-Woverride-init]
     211 |         [ESR_ELx_EC_IABT_LOW]           = kvm_hyp_handle_iabt_low,
         |                                           ^~~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:211:43: note: (near initialization for 'pvm_exit_handlers[32]')
   arch/arm64/kvm/hyp/nvhe/switch.c:212:43: warning: initialized field overwritten [-Woverride-init]
     212 |         [ESR_ELx_EC_DABT_LOW]           = kvm_hyp_handle_dabt_low,
         |                                           ^~~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:212:43: note: (near initialization for 'pvm_exit_handlers[36]')
   arch/arm64/kvm/hyp/nvhe/switch.c:213:43: warning: initialized field overwritten [-Woverride-init]
     213 |         [ESR_ELx_EC_PAC]                = kvm_hyp_handle_ptrauth,
         |                                           ^~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:213:43: note: (near initialization for 'pvm_exit_handlers[9]')
   arch/arm64/kvm/hyp/nvhe/switch.c:350:17: warning: no previous prototype for 'hyp_panic' [-Wmissing-prototypes]
     350 | void __noreturn hyp_panic(void)
         |                 ^~~~~~~~~
>> arch/arm64/kvm/hyp/nvhe/switch.c:372:17: warning: no previous prototype for 'hyp_panic_bad_stack' [-Wmissing-prototypes]
     372 | void __noreturn hyp_panic_bad_stack(void)
         |                 ^~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:377:17: warning: no previous prototype for 'kvm_unexpected_el2_exception' [-Wmissing-prototypes]
     377 | asmlinkage void kvm_unexpected_el2_exception(void)
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/hyp_panic_bad_stack +372 arch/arm64/kvm/hyp/nvhe/switch.c

   371	
 > 372	void __noreturn hyp_panic_bad_stack(void)
   373	{
   374		hyp_panic();
   375	}
   376	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
kernel test robot Feb. 23, 2022, 9:05 a.m. UTC | #2 
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@intel.com/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@intel.com>

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)
                ^~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:201:27: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [ESR_ELx_EC_IABT_LOW]           = kvm_hyp_handle_iabt_low,
                                             ^~~~~~~~~~~~~~~~~~~~~~~
   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)
                ^~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:202:27: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [ESR_ELx_EC_DABT_LOW]           = kvm_hyp_handle_dabt_low,
                                             ^~~~~~~~~~~~~~~~~~~~~~~
   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)
                ^~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:203:22: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [ESR_ELx_EC_PAC]                = kvm_hyp_handle_ptrauth,
                                             ^~~~~~~~~~~~~~~~~~~~~~
   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)
                ^~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:208:24: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [ESR_ELx_EC_SYS64]              = kvm_handle_pvm_sys64,
                                             ^~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:207:28: 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)
                ^~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:209:22: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [ESR_ELx_EC_SVE]                = kvm_handle_pvm_restricted,
                                             ^~~~~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:207:28: 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)
                ^~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:210:27: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [ESR_ELx_EC_FP_ASIMD]           = kvm_handle_pvm_fpsimd,
                                             ^~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:207:28: 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)
                ^~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:211:27: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [ESR_ELx_EC_IABT_LOW]           = kvm_hyp_handle_iabt_low,
                                             ^~~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:207:28: 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)
                ^~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:212:27: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [ESR_ELx_EC_DABT_LOW]           = kvm_hyp_handle_dabt_low,
                                             ^~~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:207:28: 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)
                ^~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:213:22: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides]
           [ESR_ELx_EC_PAC]                = kvm_hyp_handle_ptrauth,
                                             ^~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:207:28: 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)
                ^~~~~~~~~~~
   arch/arm64/kvm/hyp/nvhe/switch.c:350:17: warning: no previous prototype for function 'hyp_panic' [-Wmissing-prototypes]
   void __noreturn hyp_panic(void)
                   ^
   arch/arm64/kvm/hyp/nvhe/switch.c:350:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void __noreturn hyp_panic(void)
   ^
   static 
>> 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)
                   ^
   arch/arm64/kvm/hyp/nvhe/switch.c:372:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void __noreturn hyp_panic_bad_stack(void)
   ^
   static 
   arch/arm64/kvm/hyp/nvhe/switch.c:377:17: warning: no previous prototype for function 'kvm_unexpected_el2_exception' [-Wmissing-prototypes]
   asmlinkage void kvm_unexpected_el2_exception(void)
                   ^
   arch/arm64/kvm/hyp/nvhe/switch.c:377:12: note: declare 'static' if the function is not intended to be used outside of this translation unit
   asmlinkage void kvm_unexpected_el2_exception(void)
              ^
              static 
   16 warnings generated.


vim +/hyp_panic_bad_stack +372 arch/arm64/kvm/hyp/nvhe/switch.c

   371	
 > 372	void __noreturn hyp_panic_bad_stack(void)
   373	{
   374		hyp_panic();
   375	}
   376	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Marc Zyngier Feb. 23, 2022, 9:16 a.m. UTC | #3 
On Wed, 23 Feb 2022 09:05:18 +0000,
kernel test robot <lkp@intel.com> 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@intel.com/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@intel.com>
> 
> 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.

	M.
Philip Li Feb. 23, 2022, 12:34 p.m. UTC | #4 
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@intel.com> 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@intel.com/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@intel.com>
> > 
> > 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)
                   ^
Thanks

> 
> 	M.
> 
> -- 
> Without deviation from the norm, progress is not possible.
> _______________________________________________
> kbuild-all mailing list -- kbuild-all@lists.01.org
> To unsubscribe send an email to kbuild-all-leave@lists.01.org
Marc Zyngier Feb. 23, 2022, 12:54 p.m. UTC | #5 
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@intel.com> 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@intel.com/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@intel.com>
>> >
>> > 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.
Ard Biesheuvel Feb. 23, 2022, 12:56 p.m. UTC | #6 
On Wed, 23 Feb 2022 at 13:54, Marc Zyngier <maz@kernel.org> wrote:
>
> 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@intel.com> 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@intel.com/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@intel.com>
> >> >
> >> > 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.
>

Should probably be marked as 'asmlinkage' then. I've suggested many
times already that this bogus diagnostic should either be disabled, or
disregard 'asmlinkage' symbols.
Marc Zyngier Feb. 24, 2022, 10:39 a.m. UTC | #7 
On 2022-02-23 12:56, Ard Biesheuvel wrote:
> On Wed, 23 Feb 2022 at 13:54, Marc Zyngier <maz@kernel.org> wrote:
>> 
>> 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@intel.com> 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@intel.com/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@intel.com>
>> >> >
>> >> > 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.
>> 
> 
> Should probably be marked as 'asmlinkage' then. I've suggested many
> times already that this bogus diagnostic should either be disabled, or
> disregard 'asmlinkage' symbols.

Yes, asmlinkage is definitely missing.

But it is pretty obvious that the robot people aren't interested in
fixing this particular issue, given how long we have been suggesting
this...

         M.
Chen, Rong A Feb. 25, 2022, 2:12 a.m. UTC | #8 
On 2/24/2022 6:39 PM, Marc Zyngier wrote:
> On 2022-02-23 12:56, Ard Biesheuvel wrote:
>> On Wed, 23 Feb 2022 at 13:54, Marc Zyngier <maz@kernel.org> wrote:
>>>
>>> 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@intel.com> 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@intel.com/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@intel.com>
>>> >> >
>>> >> > 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.
>>>
>>
>> Should probably be marked as 'asmlinkage' then. I've suggested many
>> times already that this bogus diagnostic should either be disabled, or
>> disregard 'asmlinkage' symbols.
> 
> Yes, asmlinkage is definitely missing.
> 
> But it is pretty obvious that the robot people aren't interested in
> fixing this particular issue, given how long we have been suggesting
> this...
> 
>          M.

Hi Marc, Ard,

We have ignored the warning related to asmlinkage according to the below 
advice:
 
https://lore.kernel.org/lkml/CAMj1kXHrRYagSVniSetHdG15rkQS+fm4zVOtN=Zda3W0QaEoJA@mail.gmail.com/

do you want the bot ignore such warning if asmlinkage not specified?

Best Regards,
Rong Chen
Kalesh Singh Feb. 25, 2022, 3:11 a.m. UTC | #9 
On Thu, Feb 24, 2022 at 6:12 PM Chen, Rong A <rong.a.chen@intel.com> wrote:
>
>
>
> On 2/24/2022 6:39 PM, Marc Zyngier wrote:
> > On 2022-02-23 12:56, Ard Biesheuvel wrote:
> >> On Wed, 23 Feb 2022 at 13:54, Marc Zyngier <maz@kernel.org> wrote:
> >>>
> >>> 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@intel.com> 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@intel.com/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@intel.com>
> >>> >> >
> >>> >> > 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.
> >>>
> >>
> >> Should probably be marked as 'asmlinkage' then. I've suggested many
> >> times already that this bogus diagnostic should either be disabled, or
> >> disregard 'asmlinkage' symbols.
> >
> > Yes, asmlinkage is definitely missing.
> >
> > But it is pretty obvious that the robot people aren't interested in
> > fixing this particular issue, given how long we have been suggesting
> > this...
> >
> >          M.
>
> Hi Marc, Ard,
>
> We have ignored the warning related to asmlinkage according to the below
> advice:
>
> https://lore.kernel.org/lkml/CAMj1kXHrRYagSVniSetHdG15rkQS+fm4zVOtN=Zda3W0QaEoJA@mail.gmail.com/
>
> do you want the bot ignore such warning if asmlinkage not specified?

Hi Rong,

I have added asmlinkage to the functions without a prototype in later
versions of the patch.

Perhaps the report should be updated to say "functions only called
from assembly code should be annotated with the asmlinkage attribute"
if the error is a missing prototype

Thanks,
Kalesh
>
> Best Regards,
> Rong Chen
>
> --
> To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com.
>
Marc Zyngier Feb. 25, 2022, 3:31 p.m. UTC | #10 
On Fri, 25 Feb 2022 02:12:32 +0000,
"Chen, Rong A" <rong.a.chen@intel.com> wrote:
> 
> Hi Marc, Ard,
> 
> We have ignored the warning related to asmlinkage according to the
> below advice:
> 
> https://lore.kernel.org/lkml/CAMj1kXHrRYagSVniSetHdG15rkQS+fm4zVOtN=Zda3W0QaEoJA@mail.gmail.com/

Ah, I didn't realise it had been updated. Apologies for the shouting!

> do you want the bot ignore such warning if asmlinkage not specified?

No, there is some value in warning about this particular case.

Thanks,

	M.
Ard Biesheuvel Feb. 25, 2022, 3:38 p.m. UTC | #11 
On Fri, 25 Feb 2022 at 03:12, Chen, Rong A <rong.a.chen@intel.com> wrote:
>
>
>

> Hi Marc, Ard,
>
> We have ignored the warning related to asmlinkage according to the below
> advice:
>
> https://lore.kernel.org/lkml/CAMj1kXHrRYagSVniSetHdG15rkQS+fm4zVOtN=Zda3W0QaEoJA@mail.gmail.com/
>

Excellent! Thanks for implementing this - I wasn't aware that you
adopted this suggestion.

> do you want the bot ignore such warning if asmlinkage not specified?
>

Even though I think this warning has little value, I think asmlinkage
is sufficient for us to avoid it for symbols that are exported for use
by assembler code.

So I don't think this additional change is needed.
diff mbox series

Patch

diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 3d613e721a75..78e4b612ac06 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -153,6 +153,10 @@  SYM_FUNC_END(__host_hvc)
 
 .macro invalid_host_el2_vect
 	.align 7
+
+	/* Test stack overflow without corrupting GPRs */
+	test_sp_overflow PAGE_SHIFT, .L__hyp_sp_overflow\@
+
 	/* If a guest is loaded, panic out of it. */
 	stp	x0, x1, [sp, #-16]!
 	get_loaded_vcpu x0, x1
@@ -165,6 +169,18 @@  SYM_FUNC_END(__host_hvc)
 	 * been partially clobbered by __host_enter.
 	 */
 	b	hyp_panic
+
+.L__hyp_sp_overflow\@:
+	/*
+	 * Reset SP to the top of the stack, to allow handling the hyp_panic.
+	 * This corrupts the stack but is ok, since we won't be attempting
+	 * any unwinding here.
+	 */
+	ldr_this_cpu	x0, kvm_init_params + NVHE_INIT_STACK_HYP_VA, x1
+	mov	sp, x0
+
+	bl	hyp_panic_bad_stack
+	ASM_BUG()
 .endm
 
 .macro invalid_host_el1_vect
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 6410d21d8695..5a2e1ab79913 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -369,6 +369,11 @@  void __noreturn hyp_panic(void)
 	unreachable();
 }
 
+void __noreturn hyp_panic_bad_stack(void)
+{
+	hyp_panic();
+}
+
 asmlinkage void kvm_unexpected_el2_exception(void)
 {
 	return __kvm_unexpected_el2_exception();