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SubjectRe: [PATCH v7 7/9] mm: Add address parameter to arch_validate_prot()
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On 08/10/2017 07:20 AM, Michael Ellerman wrote:
> Khalid Aziz <khalid.aziz@oracle.com> writes:
>
>> A protection flag may not be valid across entire address space and
>> hence arch_validate_prot() might need the address a protection bit is
>> being set on to ensure it is a valid protection flag. For example, sparc
>> processors support memory corruption detection (as part of ADI feature)
>> flag on memory addresses mapped on to physical RAM but not on PFN mapped
>> pages or addresses mapped on to devices. This patch adds address to the
>> parameters being passed to arch_validate_prot() so protection bits can
>> be validated in the relevant context.
>>
>> Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com>
>> Cc: Khalid Aziz <khalid@gonehiking.org>
>> ---
>> v7:
>> - new patch
>>
>> arch/powerpc/include/asm/mman.h | 2 +-
>> arch/powerpc/kernel/syscalls.c | 2 +-
>> include/linux/mman.h | 2 +-
>> mm/mprotect.c | 2 +-
>> 4 files changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/powerpc/include/asm/mman.h b/arch/powerpc/include/asm/mman.h
>> index 30922f699341..bc74074304a2 100644
>> --- a/arch/powerpc/include/asm/mman.h
>> +++ b/arch/powerpc/include/asm/mman.h
>> @@ -40,7 +40,7 @@ static inline bool arch_validate_prot(unsigned long prot)
>> return false;
>> return true;
>> }
>> -#define arch_validate_prot(prot) arch_validate_prot(prot)
>> +#define arch_validate_prot(prot, addr) arch_validate_prot(prot)
>
> This can be simpler, as just:
>
> #define arch_validate_prot arch_validate_prot
>

Hi Michael,

Thanks for reviewing!

My patch expands parameter list for arch_validate_prot() from one to two
parameters. Existing powerpc version of arch_validate_prot() is written
with one parameter. If I use the above #define, compilation fails with:

mm/mprotect.c: In function ‘do_mprotect_pkey’:
mm/mprotect.c:399: error: too many arguments to function
‘arch_validate_prot’

Another way to solve it would be to add the new addr parameter to
powerpc version of arch_validate_prot() but I chose the less disruptive
solution of tackling it through #define and expanded the existing
#define to include the new parameter. Make sense?

Thanks,
Khalid

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