Hi Christophe,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on powerpc/next]
[also build test ERROR on v5.0-rc4 next-20190221]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Russell-Currey/Kernel-Userspace-Protection-for-radix/20190221-193749
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-allyesconfig (attached as .config)
compiler: powerpc64-linux-gnu-gcc (Debian 8.2.0-11) 8.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=8.2.0 make.cross ARCH=powerpc 

Note: the linux-review/Russell-Currey/Kernel-Userspace-Protection-for-radix/20190221-193749 HEAD 5f2951ce63da41c63227ed597252cea801adb5a4 builds fine.
      It only hurts bisectibility.

All errors (new ones prefixed by >>):

   In file included from arch/powerpc/kernel/asm-offsets.c:31:
   arch/powerpc/kernel/asm-offsets.c: In function 'main':
>> include/linux/compiler_types.h:127:35: error: 'struct paca_struct' has no member named 'user_access_allowed'
    #define __compiler_offsetof(a, b) __builtin_offsetof(a, b)
                                      ^~~~~~~~~~~~~~~~~~
   include/linux/kbuild.h:6:62: note: in definition of macro 'DEFINE'
     asm volatile("\n.ascii \"->" #sym " %0 " #val "\"" : : "i" (val))
                                                                 ^~~
   include/linux/stddef.h:17:32: note: in expansion of macro '__compiler_offsetof'
    #define offsetof(TYPE, MEMBER) __compiler_offsetof(TYPE, MEMBER)
                                   ^~~~~~~~~~~~~~~~~~~
   include/linux/kbuild.h:11:14: note: in expansion of macro 'offsetof'
     DEFINE(sym, offsetof(struct str, mem))
                 ^~~~~~~~
   arch/powerpc/kernel/asm-offsets.c:266:2: note: in expansion of macro 'OFFSET'
     OFFSET(PACA_USER_ACCESS_ALLOWED, paca_struct, user_access_allowed);
     ^~~~~~
   make[2]: *** [arch/powerpc/kernel/asm-offsets.s] Error 1
   make[2]: Target '__build' not remade because of errors.
   make[1]: *** [prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [sub-make] Error 2

vim +127 include/linux/compiler_types.h

71391bdd Xiaozhou Liu 2018-12-14  126  
71391bdd Xiaozhou Liu 2018-12-14 @127  #define __compiler_offsetof(a, b)	__builtin_offsetof(a, b)
71391bdd Xiaozhou Liu 2018-12-14  128  

:::::: The code at line 127 was first introduced by commit
:::::: 71391bdd2e9aab188f86bf1ecd9b232531ec7eea include/linux/compiler_types.h: don't pollute userspace with macro definitions

:::::: TO: Xiaozhou Liu <liuxiaozhou@bytedance.com>
:::::: CC: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>

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0-DAY kernel test infrastructure                Open Source Technology Center
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