[PATCH v4 10/16] arm64/mm: ptep_set_wrprotect(): 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 | 10 ++++++----
 arch/arm64/mm/hugetlbpage.c      |  2 +-
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index fc1005222ee4..423cc32b2777 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -958,11 +958,11 @@ static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm,
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 /*
- * ptep_set_wrprotect - mark read-only while trasferring potential hardware
+ * __ptep_set_wrprotect - mark read-only while trasferring potential hardware
  * dirty status (PTE_DBM && !PTE_RDONLY) to the software PTE_DIRTY bit.
  */
-#define __HAVE_ARCH_PTEP_SET_WRPROTECT
-static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep)
+static inline void __ptep_set_wrprotect(struct mm_struct *mm,
+					unsigned long address, pte_t *ptep)
 {
 	pte_t old_pte, pte;
 
@@ -980,7 +980,7 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
 static inline void pmdp_set_wrprotect(struct mm_struct *mm,
 				      unsigned long address, pmd_t *pmdp)
 {
-	ptep_set_wrprotect(mm, address, (pte_t *)pmdp);
+	__ptep_set_wrprotect(mm, address, (pte_t *)pmdp);
 }
 
 #define pmdp_establish pmdp_establish
@@ -1120,6 +1120,8 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma,
 #define ptep_test_and_clear_young		__ptep_test_and_clear_young
 #define __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
 #define ptep_clear_flush_young			__ptep_clear_flush_young
+#define __HAVE_ARCH_PTEP_SET_WRPROTECT
+#define ptep_set_wrprotect			__ptep_set_wrprotect
 
 #endif /* !__ASSEMBLY__ */
 
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index c2a753541d13..952462820d9d 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -493,7 +493,7 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm,
 	pte_t pte;
 
 	if (!pte_cont(READ_ONCE(*ptep))) {
-		ptep_set_wrprotect(mm, addr, ptep);
+		__ptep_set_wrprotect(mm, addr, ptep);
 		return;
 	}
 
-- 
2.25.1