[PATCH V3 2/5] mm: update ptep_modify_prot_commit to take old pte value as arg

[Aneesh Kumar K.V]

On 12/5/18 9:32 AM, Christophe LEROY wrote:
> 
> 
> Le 05/12/2018 à 04:09, Aneesh Kumar K.V a écrit :
>> Architectures like ppc64 requires to do a conditional tlb flush based 
>> on the old
>> and new value of pte. Enable that by passing old pte value as the arg.
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
>> ---
>>   arch/s390/include/asm/pgtable.h | 3 ++-
>>   arch/s390/mm/pgtable.c          | 2 +-
>>   arch/x86/include/asm/paravirt.h | 2 +-
>>   fs/proc/task_mmu.c              | 8 +++++---
>>   include/asm-generic/pgtable.h   | 2 +-
>>   mm/memory.c                     | 8 ++++----
>>   mm/mprotect.c                   | 6 +++---
>>   7 files changed, 17 insertions(+), 14 deletions(-)
>>
>> diff --git a/arch/s390/include/asm/pgtable.h 
>> b/arch/s390/include/asm/pgtable.h
>> index 5d730199e37b..76dc344edb8c 100644
>> --- a/arch/s390/include/asm/pgtable.h
>> +++ b/arch/s390/include/asm/pgtable.h
>> @@ -1070,7 +1070,8 @@ static inline pte_t ptep_get_and_clear(struct 
>> mm_struct *mm,
>>   #define __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
>>   pte_t ptep_modify_prot_start(struct vm_area_struct *, unsigned long, 
>> pte_t *);
>> -void ptep_modify_prot_commit(struct vm_area_struct *, unsigned long, 
>> pte_t *, pte_t);
>> +void ptep_modify_prot_commit(struct vm_area_struct *, unsigned long,
>> +                 pte_t *, pte_t, pte_t);
>>   #define __HAVE_ARCH_PTEP_CLEAR_FLUSH
>>   static inline pte_t ptep_clear_flush(struct vm_area_struct *vma,
>> diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
>> index 29c0a21cd34a..b283b92722cc 100644
>> --- a/arch/s390/mm/pgtable.c
>> +++ b/arch/s390/mm/pgtable.c
>> @@ -322,7 +322,7 @@ pte_t ptep_modify_prot_start(struct vm_area_struct 
>> *vma, unsigned long addr,
>>   EXPORT_SYMBOL(ptep_modify_prot_start);
>>   void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned 
>> long addr,
>> -                 pte_t *ptep, pte_t pte)
>> +                 pte_t *ptep, pte_t old_pte, pte_t pte)
>>   {
>>       pgste_t pgste;
>>       struct mm_struct *mm = vma->vm_mm;
>> diff --git a/arch/x86/include/asm/paravirt.h 
>> b/arch/x86/include/asm/paravirt.h
>> index 1154f154025d..0d75a4f60500 100644
>> --- a/arch/x86/include/asm/paravirt.h
>> +++ b/arch/x86/include/asm/paravirt.h
>> @@ -429,7 +429,7 @@ static inline pte_t ptep_modify_prot_start(struct 
>> vm_area_struct *vma, unsigned
>>   }
>>   static inline void ptep_modify_prot_commit(struct vm_area_struct 
>> *vma, unsigned long addr,
>> -                       pte_t *ptep, pte_t pte)
>> +                       pte_t *ptep, pte_t old_pte, pte_t pte)
>>   {
>>       struct mm_struct *mm = vma->vm_mm;
>> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
>> index 9952d7185170..8d62891d38a8 100644
>> --- a/fs/proc/task_mmu.c
>> +++ b/fs/proc/task_mmu.c
>> @@ -940,10 +940,12 @@ static inline void clear_soft_dirty(struct 
>> vm_area_struct *vma,
>>       pte_t ptent = *pte;
>>       if (pte_present(ptent)) {
>> -        ptent = ptep_modify_prot_start(vma, addr, pte);
>> -        ptent = pte_wrprotect(ptent);
>> +        pte_t old_pte;
>> +
>> +        old_pte = ptep_modify_prot_start(vma, addr, pte);
>> +        ptent = pte_wrprotect(old_pte);
> 
> This change doesn't seem to fit with the commit description. Why write 
> protecting in addition to clearing dirty ?
> 
>

The hunk above use a new variable old_pte. There is no functional change 
in that hunk.

-aneesh