4 files changed, 38 insertions, 13 deletions

diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index fb1b93ea3e3f..e485817f7b1a 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -15,17 +15,25 @@
 static inline int init_new_context(struct task_struct *tsk,
                                    struct mm_struct *mm)
 {
+        spin_lock_init(&mm->context.list_lock);
+        INIT_LIST_HEAD(&mm->context.pgtable_list);
+        INIT_LIST_HEAD(&mm->context.gmap_list);
         cpumask_clear(&mm->context.cpu_attach_mask);
         atomic_set(&mm->context.attach_count, 0);
         mm->context.flush_mm = 0;
-        mm->context.asce_bits = _ASCE_TABLE_LENGTH | _ASCE_USER_BITS;
-        mm->context.asce_bits |= _ASCE_TYPE_REGION3;
 #ifdef CONFIG_PGSTE
         mm->context.alloc_pgste = page_table_allocate_pgste;
         mm->context.has_pgste = 0;
         mm->context.use_skey = 0;
 #endif
-        mm->context.asce_limit = STACK_TOP_MAX;
+        if (mm->context.asce_limit == 0) {
+                /* context created by exec, set asce limit to 4TB */
+                mm->context.asce_bits = _ASCE_TABLE_LENGTH |
+                        _ASCE_USER_BITS | _ASCE_TYPE_REGION3;
+                mm->context.asce_limit = STACK_TOP_MAX;
+        } else if (mm->context.asce_limit == (1UL << 31)) {
+                mm_inc_nr_pmds(mm);
+        }
         crst_table_init((unsigned long *) mm->pgd, pgd_entry_type(mm));
         return 0;
 }
@@ -111,8 +119,6 @@ static inline void activate_mm(struct mm_struct *prev,
 static inline void arch_dup_mmap(struct mm_struct *oldmm,
                                  struct mm_struct *mm)
 {
-        if (oldmm->context.asce_limit < mm->context.asce_limit)
-                crst_table_downgrade(mm, oldmm->context.asce_limit);
 }
 
 static inline void arch_exit_mmap(struct mm_struct *mm)
diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index 7b7858f158b4..d7cc79fb6191 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -100,12 +100,26 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
 
 static inline pgd_t *pgd_alloc(struct mm_struct *mm)
 {
-        spin_lock_init(&mm->context.list_lock);
-        INIT_LIST_HEAD(&mm->context.pgtable_list);
-        INIT_LIST_HEAD(&mm->context.gmap_list);
-        return (pgd_t *) crst_table_alloc(mm);
+        unsigned long *table = crst_table_alloc(mm);
+
+        if (!table)
+                return NULL;
+        if (mm->context.asce_limit == (1UL << 31)) {
+                /* Forking a compat process with 2 page table levels */
+                if (!pgtable_pmd_page_ctor(virt_to_page(table))) {
+                        crst_table_free(mm, table);
+                        return NULL;
+                }
+        }
+        return (pgd_t *) table;
+}
+
+static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
+{
+        if (mm->context.asce_limit == (1UL << 31))
+                pgtable_pmd_page_dtor(virt_to_page(pgd));
+        crst_table_free(mm, (unsigned long *) pgd);
 }
-#define pgd_free(mm, pgd) crst_table_free(mm, (unsigned long *) pgd)
 
 static inline void pmd_populate(struct mm_struct *mm,
                                 pmd_t *pmd, pgtable_t pte)
diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S
index c5febe84eba6..03c2b469c472 100644
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -16,7 +16,7 @@
 
 __HEAD
 ENTRY(startup_continue)
-        tm      __LC_STFLE_FAC_LIST+6,0x80      # LPP available ?
+        tm      __LC_STFLE_FAC_LIST+5,0x80      # LPP available ?
         jz      0f
         xc      __LC_LPP+1(7,0),__LC_LPP+1      # clear lpp and current_pid
         mvi     __LC_LPP,0x80                   #   and set LPP_MAGIC
diff --git a/drivers/s390/block/dasd_diag.c b/drivers/s390/block/dasd_diag.c
index cb61f300f8b5..277b5c8c825c 100644
--- a/drivers/s390/block/dasd_diag.c
+++ b/drivers/s390/block/dasd_diag.c
@@ -67,7 +67,7 @@ static const u8 DASD_DIAG_CMS1[] = { 0xc3, 0xd4, 0xe2, 0xf1 };/* EBCDIC CMS1 */
  * and function code cmd.
  * In case of an exception return 3. Otherwise return result of bitwise OR of
  * resulting condition code and DIAG return code. */
-static inline int dia250(void *iob, int cmd)
+static inline int __dia250(void *iob, int cmd)
 {
         register unsigned long reg2 asm ("2") = (unsigned long) iob;
         typedef union {
@@ -77,7 +77,6 @@ static inline int dia250(void *iob, int cmd)
         int rc;
 
         rc = 3;
-        diag_stat_inc(DIAG_STAT_X250);
         asm volatile(
                 "       diag    2,%2,0x250\n"
                 "0:     ipm     %0\n"
@@ -91,6 +90,12 @@ static inline int dia250(void *iob, int cmd)
         return rc;
 }
 
+static inline int dia250(void *iob, int cmd)
+{
+        diag_stat_inc(DIAG_STAT_X250);
+        return __dia250(iob, cmd);
+}
+
 /* Initialize block I/O to DIAG device using the specified blocksize and
  * block offset. On success, return zero and set end_block to contain the
  * number of blocks on the device minus the specified offset. Return non-zero