[RFC V2 09/14] arm64/mm: Route all pgtable atomics to central helpers

[Anshuman Khandual]

Route all cmpxchg() operations performed on various page table entries to a
new pxxval_cmpxchg_relaxed() helper. Similarly route all xchg() operations
performed on page table entries to a new pxxval_xchg_relaxed() helper.

Currently these helpers just forward to the same APIs that were previously
called direct, but in future we will change the routing for D128 which is
too long to use the standard APIs.

Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Ryan Roberts <ryan.roberts@xxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
Changes in RFC V2:

- Renamed all ptdesc_ instances as pxxval_ instead

 arch/arm64/include/asm/pgtable.h | 23 +++++++++++++++++------
 arch/arm64/mm/fault.c            |  2 +-
 2 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index c71bb829e9f1..f876200d383e 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -87,6 +87,17 @@ static inline void arch_leave_lazy_mmu_mode(void)
 #define pxxval_get(x)		READ_ONCE(x)
 #define pxxval_set(x, val)	WRITE_ONCE(x, val)
 
+static inline ptdesc_t pxxval_cmpxchg_relaxed(ptdesc_t *ptep, ptdesc_t old,
+					      ptdesc_t new)
+{
+	return cmpxchg_relaxed(ptep, old, new);
+}
+
+static inline ptdesc_t pxxval_xchg_relaxed(ptdesc_t *ptep, ptdesc_t new)
+{
+	return xchg_relaxed(ptep, new);
+}
+
 #define pmdp_get pmdp_get
 static inline pmd_t pmdp_get(pmd_t *pmdp)
 {
@@ -1340,8 +1351,8 @@ static inline bool __ptep_test_and_clear_young(struct vm_area_struct *vma,
 	do {
 		old_pte = pte;
 		pte = pte_mkold(pte);
-		pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
-					       pte_val(old_pte), pte_val(pte));
+		pte_val(pte) = pxxval_cmpxchg_relaxed(&pte_val(*ptep),
+						      pte_val(old_pte), pte_val(pte));
 	} while (pte_val(pte) != pte_val(old_pte));
 
 	return pte_young(pte);
@@ -1383,7 +1394,7 @@ static inline pte_t __ptep_get_and_clear_anysz(struct mm_struct *mm,
 					       pte_t *ptep,
 					       unsigned long pgsize)
 {
-	pte_t pte = __pte(xchg_relaxed(&pte_val(*ptep), 0));
+	pte_t pte = __pte(pxxval_xchg_relaxed(&pte_val(*ptep), 0));
 
 	switch (pgsize) {
 	case PAGE_SIZE:
@@ -1459,7 +1470,7 @@ static inline void ___ptep_set_wrprotect(struct mm_struct *mm,
 	do {
 		old_pte = pte;
 		pte = pte_wrprotect(pte);
-		pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
+		pte_val(pte) = pxxval_cmpxchg_relaxed(&pte_val(*ptep),
 					       pte_val(old_pte), pte_val(pte));
 	} while (pte_val(pte) != pte_val(old_pte));
 }
@@ -1497,7 +1508,7 @@ static inline void __clear_young_dirty_pte(struct vm_area_struct *vma,
 		if (flags & CYDP_CLEAR_DIRTY)
 			pte = pte_mkclean(pte);
 
-		pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
+		pte_val(pte) = pxxval_cmpxchg_relaxed(&pte_val(*ptep),
 					       pte_val(old_pte), pte_val(pte));
 	} while (pte_val(pte) != pte_val(old_pte));
 }
@@ -1536,7 +1547,7 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
 		unsigned long address, pmd_t *pmdp, pmd_t pmd)
 {
 	page_table_check_pmd_set(vma->vm_mm, address, pmdp, pmd);
-	return __pmd(xchg_relaxed(&pmd_val(*pmdp), pmd_val(pmd)));
+	return __pmd(pxxval_xchg_relaxed(&pmd_val(*pmdp), pmd_val(pmd)));
 }
 #endif
 
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 5c61f39f7f29..bce191d16090 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -232,7 +232,7 @@ int __ptep_set_access_flags_anysz(struct vm_area_struct *vma,
 		pteval ^= PTE_RDONLY;
 		pteval |= pte_val(entry);
 		pteval ^= PTE_RDONLY;
-		pteval = cmpxchg_relaxed(&pte_val(*ptep), old_pteval, pteval);
+		pteval = pxxval_cmpxchg_relaxed(&pte_val(*ptep), old_pteval, pteval);
 	} while (pteval != old_pteval);
 
 	/*
-- 
2.43.0