On 09/01/2020 01:06 PM, Aneesh Kumar K.V wrote:
> On 9/1/20 1:02 PM, Anshuman Khandual wrote:
>>
>>
>> On 09/01/2020 11:51 AM, Aneesh Kumar K.V wrote:
>>> On 9/1/20 8:45 AM, Anshuman Khandual wrote:
>>>>
>>>>
>>>> On 08/27/2020 01:34 PM, Aneesh Kumar K.V wrote:
>>>>> ppc64 use bit 62 to indicate a pte entry (_PAGE_PTE). Avoid setting that
>>>>> bit in
>>>>> random value.
>>>>>
>>>>> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
>>>>> ---
>>>>> mm/debug_vm_pgtable.c | 13 ++++++++++---
>>>>> 1 file changed, 10 insertions(+), 3 deletions(-)
>>>>>
>>>>> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
>>>>> index 086309fb9b6f..bbf9df0e64c6 100644
>>>>> --- a/mm/debug_vm_pgtable.c
>>>>> +++ b/mm/debug_vm_pgtable.c
>>>>> @@ -44,10 +44,17 @@
>>>>> * entry type. But these bits might affect the ability to clear
>>>>> entries with
>>>>> * pxx_clear() because of how dynamic page table folding works on
>>>>> s390. So
>>>>> * while loading up the entries do not change the lower 4 bits. It
>>>>> does not
>>>>> - * have affect any other platform.
>>>>> + * have affect any other platform. Also avoid the 62nd bit on ppc64 that
>>>>> is
>>>>> + * used to mark a pte entry.
>>>>> */
>>>>> -#define S390_MASK_BITS 4
>>>>> -#define RANDOM_ORVALUE GENMASK(BITS_PER_LONG - 1, S390_MASK_BITS)
>>>>> +#define S390_SKIP_MASK GENMASK(3, 0)
>>>>> +#ifdef CONFIG_PPC_BOOK3S_64
>>>>> +#define PPC64_SKIP_MASK GENMASK(62, 62)
>>>>> +#else
>>>>> +#define PPC64_SKIP_MASK 0x0
>>>>> +#endif
>>>>
>>>> Please drop the #ifdef CONFIG_PPC_BOOK3S_64 here. We already accommodate
>>>> skip
>>>> bits for a s390 platform requirement and can also do so for ppc64 as well.
>>>> As
>>>> mentioned before, please avoid adding any platform specific constructs in
>>>> the
>>>> test.
>>>>
>>>
>>>
>>> that is needed so that it can be built on 32 bit architectures.I did face
>>> build errors with arch-linux
>>
>> Could not (#if __BITS_PER_LONG == 32) be used instead or something like
>> that. But should be a generic conditional check identifying 32 bit arch
>> not anything platform specific.
>>
>
> that _PAGE_PTE bit is pretty much specific to PPC BOOK3S_64. Not sure why
> other architectures need to bothered about ignoring bit 62.
Thats okay as long it does not adversely affect other architectures, ignoring
some more bits is acceptable. Like existing S390_MASK_BITS gets ignored on all
other platforms even if it is a s390 specific constraint. Not having platform
specific #ifdef here, is essential.
