[PATCH v3 6/9] mm: add hw_pte_val for HW PTE storage

[Muhammad Usama Anjum <usama.anjum@arm.com>]

Atomic PTE updates need an lvalue for the bits stored in an HW PTE.
pte_val() only accepts a SW PTE value, so it cannot operate directly on
a distinct hw_pte_t.

Add hw_pte_val() to expose the underlying pte_val() lvalue. Access the
wrapper's __pte member when hw_pte_t is distinct, and use pte_val()
directly when it remains an alias of pte_t.

Signed-off-by: Muhammad Usama Anjum <usama.anjum@arm.com>
---
Changes in v3:
- Moved from the arm64 series to generic series as it makes more sense
  to add this in generic with all other changes. Usually we only add
  code where its get used. But this whole series wouldn't get used
  until an arch started using HW PTEs.
---
 include/linux/pgtable_types.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/pgtable_types.h b/include/linux/pgtable_types.h
index d6c5a7548550b..ee4eace5c3e1c 100644
--- a/include/linux/pgtable_types.h
+++ b/include/linux/pgtable_types.h
@@ -9,9 +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_val(x)  pte_val((x).__pte)
 #else
 #define hw_pte_t pte_t
 #define __pte_from_hw(pte)	(pte)
+
+#define hw_pte_val(x)  pte_val(x)
 #endif
 
 #endif /* !__ASSEMBLY__ */

-- 
2.47.3