[PATCHv4 04/12] arm64: Provide pmdp_establish() helper

Kirill A. Shutemov
2017-12-13T10:57:48Z

From: Catalin Marinas <catalin.marinas@arm.com>

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.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
arch/arm64/include/asm/pgtable.h | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 149d05fb9421..116d610a2620 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -676,6 +676,13 @@ 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];
--
2.15.0

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