[PATCH 3/6] arm64: convert between HW PTEs and SW PTE values

[Muhammad Usama Anjum]

__ptep_get() returns a SW PTE value, and __set_pte_nosync() accepts one.
When HW PTEs use a distinct hw_pte_t, directly reading or writing *ptep
as a SW PTE value no longer satisfies those interfaces.

Use __pte_from_hw after READ_ONCE() to obtain a SW PTE value and add
__hw_pte before WRITE_ONCE() to form an HW PTE.

Define __hw_pte for both the wrapper and alias configurations so the
same accessor code works in either case.

Signed-off-by: Muhammad Usama Anjum <usama.anjum at arm.com>
---
 arch/arm64/include/asm/pgtable.h | 4 ++--
 include/linux/pgtable_types.h    | 2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 4768ec59de555..67c4a6179e154 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -360,7 +360,7 @@ static inline pte_t pte_clear_uffd(pte_t pte)
 
 static inline void __set_pte_nosync(hw_pte_t *ptep, pte_t pte)
 {
-	WRITE_ONCE(*ptep, pte);
+	WRITE_ONCE(*ptep, __hw_pte(pte));
 }
 
 static inline void __set_pte_complete(pte_t pte)
@@ -381,7 +381,7 @@ static inline void __set_pte(hw_pte_t *ptep, pte_t pte)
 
 static inline pte_t __ptep_get(hw_pte_t *ptep)
 {
-	return READ_ONCE(*ptep);
+	return __pte_from_hw(READ_ONCE(*ptep));
 }
 
 extern void __sync_icache_dcache(pte_t pteval);
diff --git a/include/linux/pgtable_types.h b/include/linux/pgtable_types.h
index ee4eace5c3e1c..b5862a16aa497 100644
--- a/include/linux/pgtable_types.h
+++ b/include/linux/pgtable_types.h
@@ -9,11 +9,13 @@
 #ifdef CONFIG_ARCH_HAS_HW_PTE_T
 typedef struct __hw_pte_t { pte_t __pte; } hw_pte_t;
 #define __pte_from_hw(pte)	((pte).__pte)
+#define __hw_pte(pte)  ((hw_pte_t) { (pte) })
 
 #define hw_pte_val(x)  pte_val((x).__pte)
 #else
 #define hw_pte_t pte_t
 #define __pte_from_hw(pte)	(pte)
+#define __hw_pte(pte)  (pte)
 
 #define hw_pte_val(x)  pte_val(x)
 #endif

-- 
2.47.3