Re: [PATCH V3 1/2] mm/mmap: Restrict generic protection_map[] array visibility

[Anshuman Khandual <anshuman.khandual@arm.com>]

On 6/16/22 18:14, kernel test robot wrote:
> Hi Anshuman,
> 
> Thank you for the patch! Yet something to improve:
> 
> [auto build test ERROR on akpm-mm/mm-everything]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Anshuman-Khandual/mm-mmap-Drop-__SXXX-__PXXX-macros-from-across-platforms/20220616-121132
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
> config: x86_64-allyesconfig (https://download.01.org/0day-ci/archive/20220616/202206162004.ak9KTfMD-lkp@intel.com/config)
> compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
> reproduce (this is a W=1 build):
>         # https://github.com/intel-lab-lkp/linux/commit/4eb89368b130fe235d5e587bcc2eec18bb688e2d
>         git remote add linux-review https://github.com/intel-lab-lkp/linux
>         git fetch --no-tags linux-review Anshuman-Khandual/mm-mmap-Drop-__SXXX-__PXXX-macros-from-across-platforms/20220616-121132
>         git checkout 4eb89368b130fe235d5e587bcc2eec18bb688e2d
>         # save the config file
>         mkdir build_dir && cp config build_dir/.config
>         make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/
> 
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@intel.com>
> 
> All errors (new ones prefixed by >>):
> 
>    In file included from arch/x86/include/asm/percpu.h:27,
>                     from arch/x86/include/asm/preempt.h:6,
>                     from include/linux/preempt.h:78,
>                     from include/linux/spinlock.h:55,
>                     from include/linux/mmzone.h:8,
>                     from include/linux/gfp.h:6,
>                     from include/linux/mm.h:7,
>                     from arch/x86/mm/mem_encrypt_amd.c:14:
>    arch/x86/mm/mem_encrypt_amd.c: In function 'sme_early_init':
>>> arch/x86/mm/mem_encrypt_amd.c:499:36: error: 'protection_map' undeclared (first use in this function)
>      499 |         for (i = 0; i < ARRAY_SIZE(protection_map); i++)
>          |                                    ^~~~~~~~~~~~~~
>    include/linux/kernel.h:55:33: note: in definition of macro 'ARRAY_SIZE'
>       55 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
>          |                                 ^~~
>    arch/x86/mm/mem_encrypt_amd.c:499:36: note: each undeclared identifier is reported only once for each function it appears in
>      499 |         for (i = 0; i < ARRAY_SIZE(protection_map); i++)
>          |                                    ^~~~~~~~~~~~~~
>    include/linux/kernel.h:55:33: note: in definition of macro 'ARRAY_SIZE'
>       55 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
>          |                                 ^~~
>    In file included from include/linux/bits.h:22,
>                     from include/linux/ratelimit_types.h:5,
>                     from include/linux/printk.h:9,
>                     from include/asm-generic/bug.h:22,
>                     from arch/x86/include/asm/bug.h:87,
>                     from include/linux/bug.h:5,
>                     from include/linux/mmdebug.h:5,
>                     from include/linux/mm.h:6,
>                     from arch/x86/mm/mem_encrypt_amd.c:14:
>    include/linux/build_bug.h:16:51: error: bit-field '<anonymous>' width not an integer constant
>       16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
>          |                                                   ^
>    include/linux/compiler.h:240:33: note: in expansion of macro 'BUILD_BUG_ON_ZERO'
>      240 | #define __must_be_array(a)      BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0]))
>          |                                 ^~~~~~~~~~~~~~~~~
>    include/linux/kernel.h:55:59: note: in expansion of macro '__must_be_array'
>       55 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
>          |                                                           ^~~~~~~~~~~~~~~
>    arch/x86/mm/mem_encrypt_amd.c:499:25: note: in expansion of macro 'ARRAY_SIZE'
>      499 |         for (i = 0; i < ARRAY_SIZE(protection_map); i++)
>          |                         ^~~~~~~~~~

This patch fixes the build failure here.

diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index f6d038e2cd8e..d0c2ec1bb659 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -484,6 +484,8 @@ void __init early_set_mem_enc_dec_hypercall(unsigned long vaddr, int npages, boo
        enc_dec_hypercall(vaddr, npages, enc);
 }
 
+extern pgprot_t protection_map[16];
+
 void __init sme_early_init(void)
 {
        unsigned int i;
diff --git a/arch/x86/mm/pgprot.c b/arch/x86/mm/pgprot.c
index 7eca1b009af6..96eca0b2ec90 100644
--- a/arch/x86/mm/pgprot.c
+++ b/arch/x86/mm/pgprot.c
@@ -4,7 +4,7 @@
 #include <linux/mm.h>
 #include <asm/pgtable.h>
 
-static pgprot_t protection_map[16] __ro_after_init = {
+pgprot_t protection_map[16] __ro_after_init = {
        [VM_NONE]                                       = PAGE_NONE,
        [VM_READ]                                       = PAGE_READONLY,
        [VM_WRITE]                                      = PAGE_COPY,