summaryrefslogtreecommitdiffstats
path: root/arch/s390/mm/pgtable.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/s390/mm/pgtable.c')
-rw-r--r--arch/s390/mm/pgtable.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 4909dcd762e8..6effb24de6d9 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -302,6 +302,31 @@ pte_t ptep_xchg_direct(struct mm_struct *mm, unsigned long addr,
}
EXPORT_SYMBOL(ptep_xchg_direct);
+/*
+ * Caller must check that new PTE only differs in _PAGE_PROTECT HW bit, so that
+ * RDP can be used instead of IPTE. See also comments at pte_allow_rdp().
+ */
+void ptep_reset_dat_prot(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
+ pte_t new)
+{
+ preempt_disable();
+ atomic_inc(&mm->context.flush_count);
+ if (cpumask_equal(mm_cpumask(mm), cpumask_of(smp_processor_id())))
+ __ptep_rdp(addr, ptep, 0, 0, 1);
+ else
+ __ptep_rdp(addr, ptep, 0, 0, 0);
+ /*
+ * PTE is not invalidated by RDP, only _PAGE_PROTECT is cleared. That
+ * means it is still valid and active, and must not be changed according
+ * to the architecture. But writing a new value that only differs in SW
+ * bits is allowed.
+ */
+ set_pte(ptep, new);
+ atomic_dec(&mm->context.flush_count);
+ preempt_enable();
+}
+EXPORT_SYMBOL(ptep_reset_dat_prot);
+
pte_t ptep_xchg_lazy(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t new)
{