arm64: provide pmdp_establish() helper

We need an atomic way to setup pmd page table entry, avoiding races with
CPU setting dirty/accessed bits.  This is required to implement
pmdp_invalidate() that doesn't lose these bits.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>
Signed-off-by: Kirill A. Shutemov <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 89167c43ebb55b0d7716bacb8e26703cfb7fad20..094374c82db088816d6a35ec75e1658dfc446ec4 100644 (file)
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -706,6 +706,13 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm,
 {
        ptep_set_wrprotect(mm, address, (pte_t *)pmdp);
 }
+
+#define pmdp_establish pmdp_establish
+static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
+               unsigned long address, pmd_t *pmdp, pmd_t pmd)
+{
+       return __pmd(xchg_relaxed(&pmd_val(*pmdp), pmd_val(pmd)));
+}
 #endif
 
 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];