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-rw-r--r--include/asm-generic/pgtable.h57
1 files changed, 57 insertions, 0 deletions
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 44ef329531c..ef87f889ef6 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -195,6 +195,63 @@ static inline int pmd_none_or_clear_bad(pmd_t *pmd)
}
return 0;
}
+
+static inline pte_t __ptep_modify_prot_start(struct mm_struct *mm,
+ unsigned long addr,
+ pte_t *ptep)
+{
+ /*
+ * Get the current pte state, but zero it out to make it
+ * non-present, preventing the hardware from asynchronously
+ * updating it.
+ */
+ return ptep_get_and_clear(mm, addr, ptep);
+}
+
+static inline void __ptep_modify_prot_commit(struct mm_struct *mm,
+ unsigned long addr,
+ pte_t *ptep, pte_t pte)
+{
+ /*
+ * The pte is non-present, so there's no hardware state to
+ * preserve.
+ */
+ set_pte_at(mm, addr, ptep, pte);
+}
+
+#ifndef __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
+/*
+ * Start a pte protection read-modify-write transaction, which
+ * protects against asynchronous hardware modifications to the pte.
+ * The intention is not to prevent the hardware from making pte
+ * updates, but to prevent any updates it may make from being lost.
+ *
+ * This does not protect against other software modifications of the
+ * pte; the appropriate pte lock must be held over the transation.
+ *
+ * Note that this interface is intended to be batchable, meaning that
+ * ptep_modify_prot_commit may not actually update the pte, but merely
+ * queue the update to be done at some later time. The update must be
+ * actually committed before the pte lock is released, however.
+ */
+static inline pte_t ptep_modify_prot_start(struct mm_struct *mm,
+ unsigned long addr,
+ pte_t *ptep)
+{
+ return __ptep_modify_prot_start(mm, addr, ptep);
+}
+
+/*
+ * Commit an update to a pte, leaving any hardware-controlled bits in
+ * the PTE unmodified.
+ */
+static inline void ptep_modify_prot_commit(struct mm_struct *mm,
+ unsigned long addr,
+ pte_t *ptep, pte_t pte)
+{
+ __ptep_modify_prot_commit(mm, addr, ptep, pte);
+}
+#endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */
#endif /* CONFIG_MMU */
/*