[PATCH v4 08/16] arm64/mm: ptep_test_and_clear_young(): New layer to manage contig bit

[Ryan Roberts <ryan.roberts@arm.com>]

Create a new layer for the in-table PTE manipulation APIs. For now, The
existing API is prefixed with double underscore to become the
arch-private API and the public API is just a simple wrapper that calls
the private API.

The public API implementation will subsequently be used to transparently
manipulate the contiguous bit where appropriate. But since there are
already some contig-aware users (e.g. hugetlb, kernel mapper), we must
first ensure those users use the private API directly so that the future
contig-bit manipulations in the public API do not interfere with those
existing uses.

Tested-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 arch/arm64/include/asm/pgtable.h | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 994597a0bb0f..9b4a9909fd5b 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -887,8 +887,9 @@ static inline bool pud_user_accessible_page(pud_t pud)
 /*
  * Atomic pte/pmd modifications.
  */
-#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
-static inline int __ptep_test_and_clear_young(pte_t *ptep)
+static inline int __ptep_test_and_clear_young(struct vm_area_struct *vma,
+					      unsigned long address,
+					      pte_t *ptep)
 {
 	pte_t old_pte, pte;
 
@@ -903,18 +904,11 @@ static inline int __ptep_test_and_clear_young(pte_t *ptep)
 	return pte_young(pte);
 }
 
-static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
-					    unsigned long address,
-					    pte_t *ptep)
-{
-	return __ptep_test_and_clear_young(ptep);
-}
-
 #define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
 static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
 					 unsigned long address, pte_t *ptep)
 {
-	int young = ptep_test_and_clear_young(vma, address, ptep);
+	int young = __ptep_test_and_clear_young(vma, address, ptep);
 
 	if (young) {
 		/*
@@ -937,7 +931,7 @@ static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
 					    unsigned long address,
 					    pmd_t *pmdp)
 {
-	return ptep_test_and_clear_young(vma, address, (pte_t *)pmdp);
+	return __ptep_test_and_clear_young(vma, address, (pte_t *)pmdp);
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
@@ -1123,6 +1117,8 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma,
 #define pte_clear				__pte_clear
 #define __HAVE_ARCH_PTEP_GET_AND_CLEAR
 #define ptep_get_and_clear			__ptep_get_and_clear
+#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
+#define ptep_test_and_clear_young		__ptep_test_and_clear_young
 
 #endif /* !__ASSEMBLY__ */
 
-- 
2.25.1