s390/mm: remove page table downgrade support

This update consolidates page table handling code. Because
there are hardly any 31-bit binaries left we do not need to
optimize for that.

No extra efforts are needed to ensure that a compat task does
not map anything above 2GB. The TASK_SIZE limit for 31-bit
tasks is 2GB already and the generic code does check that a
resulting map address would not surpass that limit.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

1 files changed, 0 insertions, 24 deletions

diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c
index af3bddd5e568..4630fb7705ca 100644
--- a/arch/s390/mm/pgalloc.c
+++ b/arch/s390/mm/pgalloc.c
@@ -138,30 +138,6 @@ err_p4d:
 	return -ENOMEM;
 }
 
-void crst_table_downgrade(struct mm_struct *mm)
-{
-	pgd_t *pgd;
-
-	/* downgrade should only happen from 3 to 2 levels (compat only) */
-	VM_BUG_ON(mm->context.asce_limit != _REGION2_SIZE);
-
-	if (current->active_mm == mm) {
-		clear_user_asce();
-		__tlb_flush_mm(mm);
-	}
-
-	pgd = mm->pgd;
-	mm_dec_nr_pmds(mm);
-	mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN);
-	mm->context.asce_limit = _REGION3_SIZE;
-	mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
-			   _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
-	crst_table_free(mm, (unsigned long *) pgd);
-
-	if (current->active_mm == mm)
-		set_user_asce(mm);
-}
-
 static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)
 {
 	unsigned int old, new;