Re: [PATCH v6 2/7] powerpc/64s: mm: Introduce __pmdp_collapse_flush with mm_struct argument

[Rohan McLure <rmclure@linux.ibm.com>]

> On 15 Feb 2023, at 11:17 am, Rohan McLure <rmclure@linux.ibm.com> wrote:
> 
>> On 14 Feb 2023, at 5:02 pm, Christophe Leroy <christophe.leroy@csgroup.eu> wrote:
>> 
>> 
>> 
>> Le 14/02/2023 à 02:59, Rohan McLure a écrit :
>>> pmdp_collapse_flush has references in generic code with just three
>>> parameters, due to the choice of mm context being implied by the vm_area
>>> context parameter.
>>> 
>>> Define __pmdp_collapse_flush to accept an additional mm_struct *
>>> parameter, with pmdp_collapse_flush a macro that unpacks the vma and
>>> calls __pmdp_collapse_flush. The mm_struct * parameter is needed in a
>>> future patch providing Page Table Check support, which is defined in
>>> terms of mm context objects.
>>> 
>>> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
>>> ---
>>> v6: New patch
>>> ---
>>> arch/powerpc/include/asm/book3s/64/pgtable.h | 14 +++++++++++---
>>> 1 file changed, 11 insertions(+), 3 deletions(-)
>>> 
>>> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
>>> index cb4c67bf45d7..9d8b4e25f5ed 100644
>>> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
>>> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
>>> @@ -1244,14 +1244,22 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
>>>  return hash__pmdp_huge_get_and_clear(mm, addr, pmdp);
>>> }
>>> 
>>> -static inline pmd_t pmdp_collapse_flush(struct vm_area_struct *vma,
>>> - unsigned long address, pmd_t *pmdp)
>>> +static inline pmd_t __pmdp_collapse_flush(struct vm_area_struct *vma, struct mm_struct *mm,
>>> +  unsigned long address, pmd_t *pmdp)
>>> {
>>>  if (radix_enabled())
>>>  return radix__pmdp_collapse_flush(vma, address, pmdp);
>>>  return hash__pmdp_collapse_flush(vma, address, pmdp);
>>> }
>>> -#define pmdp_collapse_flush pmdp_collapse_flush
>>> +#define pmdp_collapse_flush(vma, addr, pmdp) \
>>> +({ \
>>> + struct vm_area_struct *_vma = (vma); \
>>> + pmd_t _r; \
>>> + \
>>> + _r = __pmdp_collapse_flush(_vma, _vma->vm_mm, (addr), (pmdp)); \
>>> + \
>>> + _r; \
>>> +})
>> 
>> Can you make it a static inline function instead of a ugly macro ?
> 
> Due to some header hell, it’s looking like this location only has access to
> a prototype for struct vm_area_struct. Might have to remain a macro then.
> 
> Probably don’t need to expliclty declare a variable for the macro ‘return’
> though.

It’s the same solution opted for by ptep_test_and_clear_young.

#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
#define ptep_test_and_clear_young(__vma, __addr, __ptep)	\
({								\
	__ptep_test_and_clear_young((__vma)->vm_mm, __addr, __ptep); \
})

> 
>> 
>>> 
>>> #define __HAVE_ARCH_PMDP_HUGE_GET_AND_CLEAR_FULL
>>> pmd_t pmdp_huge_get_and_clear_full(struct vm_area_struct *vma,