1 files changed, 43 insertions, 0 deletions
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index eca14547f9c1..2981e386da7b 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1070,6 +1070,49 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
 }
 #endif
 
+#ifndef ptep_try_set
+/**
+ * ptep_try_set - atomically set an empty kernel PTE
+ * @ptep: page table entry
+ * @new_pte: value to install
+ *
+ * Atomically set *@ptep to @new_pte iff *@ptep is pte_none(). Return true on
+ * success, false if the slot was already populated or the arch has no
+ * implementation.
+ *
+ * For special kernel page tables only - never user page tables. The caller must
+ * prevent concurrent teardown of @ptep and must accept that other writers may
+ * race. Concurrent clearers must use ptep_get_and_clear() so racing accesses
+ * agree on the outcome.
+ *
+ * Architectures opt in by providing a cmpxchg-based override and defining
+ * ptep_try_set as an identity macro. The generic stub returns false, which is
+ * correct for callers that fall through to oops on failure.
+ */
+static inline bool ptep_try_set(pte_t *ptep, pte_t new_pte)
+{
+	return false;
+}
+#endif
+
+#ifndef flush_tlb_before_set
+/**
+ * flush_tlb_before_set - invalidate a kernel PTE's TLB before re-setting it
+ * @addr: kernel virtual address whose PTE was just cleared
+ *
+ * Some architectures (e.g. arm64) do not allow a live page-table entry to be
+ * repointed at a different page in one step. The old entry must first be made
+ * invalid and its translation flushed from every TLB, and only then may the new
+ * entry be written.
+ *
+ * This is only for the lockless atomic kernel-PTE installers (ptep_try_set()).
+ * It must be callable with interrupts disabled.
+ */
+static inline void flush_tlb_before_set(unsigned long addr)
+{
+}
+#endif
+
 #ifndef wrprotect_ptes
 /**
  * wrprotect_ptes - Write-protect PTEs that map consecutive pages of the same