[PATCH V2 04/14] arm64/mm: Route all pgtable atomics to central helpers

[Anshuman Khandual]

Route all cmpxchg() operations performed on various page table entries to a
new ptval_cmpxchg_relaxed() helper. Similarly route all xchg() operations
performed on page table entries to a new ptval_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>
---
 arch/arm64/include/asm/pgtable.h | 26 +++++++++++++++++++-------
 arch/arm64/mm/fault.c            |  2 +-
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 692669ea2d29..66bf5bbe484e 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 ptval_get(x)		READ_ONCE(x)
 #define ptval_set(x, val)	WRITE_ONCE(x, val)
 
+static inline ptval_t ptval_cmpxchg_relaxed(ptval_t *ptep, ptval_t old,
+					      ptval_t new)
+{
+	return cmpxchg_relaxed(ptep, old, new);
+}
+
+static inline ptval_t ptval_xchg_relaxed(ptval_t *ptep, ptval_t new)
+{
+	return xchg_relaxed(ptep, new);
+}
+
 #define pmdp_get pmdp_get
 static inline pmd_t pmdp_get(pmd_t *pmdp)
 {
@@ -1281,8 +1292,8 @@ 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) = ptval_cmpxchg_relaxed(&pte_val(*ptep),
+						      pte_val(old_pte), pte_val(pte));
 	} while (pte_val(pte) != pte_val(old_pte));
 
 	return pte_young(pte);
@@ -1324,7 +1335,7 @@ 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(ptval_xchg_relaxed(&pte_val(*ptep), 0));
 
 	switch (pgsize) {
 	case PAGE_SIZE:
@@ -1400,7 +1411,7 @@ 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) = ptval_cmpxchg_relaxed(&pte_val(*ptep),
 					       pte_val(old_pte), pte_val(pte));
 	} while (pte_val(pte) != pte_val(old_pte));
 }
@@ -1438,7 +1449,7 @@ 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) = ptval_cmpxchg_relaxed(&pte_val(*ptep),
 					       pte_val(old_pte), pte_val(pte));
 	} while (pte_val(pte) != pte_val(old_pte));
 }
@@ -1477,7 +1488,7 @@ 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(ptval_xchg_relaxed(&pmd_val(*pmdp), pmd_val(pmd)));
 }
 #endif
 
@@ -1804,7 +1815,8 @@ static inline bool ptep_try_set(pte_t *ptep, pte_t new_pte)
 {
 	pteval_t old = 0;
 
-	if (!try_cmpxchg(&pte_val(*ptep), &old, pte_val(new_pte)))
+	old = ptval_cmpxchg_relaxed(&pte_val(*ptep), old, pte_val(new_pte));
+	if (old != 0)
 		return false;
 
 	/*
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 1de76ced0403..6db93371d649 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -244,7 +244,7 @@ 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 = ptval_cmpxchg_relaxed(&pte_val(*ptep), old_pteval, pteval);
 	} while (pteval != old_pteval);
 
 	/*
-- 
2.43.0