[S390] Improve address space mode selection.

Introduce user_mode to replace the two variables switch_amode and
s390_noexec. There are three valid combinations of the old values:
  1) switch_amode == 0 && s390_noexec == 0
  2) switch_amode == 1 && s390_noexec == 0
  3) switch_amode == 1 && s390_noexec == 1
They get replaced by
  1) user_mode == HOME_SPACE_MODE
  2) user_mode == PRIMARY_SPACE_MODE
  3) user_mode == SECONDARY_SPACE_MODE
The new kernel parameter user_mode=[primary,secondary,home] lets
you choose the address space mode the user space processes should
use. In addition the CONFIG_S390_SWITCH_AMODE config option
is removed.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 10 insertions, 14 deletions

diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index fc7edd6f41b6..976e273988c2 100644
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -36,7 +36,7 @@ static inline int init_new_context(struct task_struct *tsk,
                 mm->context.has_pgste = 1;
                 mm->context.alloc_pgste = 1;
         } else {
-                mm->context.noexec = s390_noexec;
+                mm->context.noexec = (user_mode == SECONDARY_SPACE_MODE);
                 mm->context.has_pgste = 0;
                 mm->context.alloc_pgste = 0;
         }
@@ -58,7 +58,7 @@ static inline void update_mm(struct mm_struct *mm, struct task_struct *tsk)
         pgd_t *pgd = mm->pgd;
 
         S390_lowcore.user_asce = mm->context.asce_bits | __pa(pgd);
-        if (switch_amode) {
+        if (user_mode != HOME_SPACE_MODE) {
                 /* Load primary space page table origin. */
                 pgd = mm->context.noexec ? get_shadow_table(pgd) : pgd;
                 S390_lowcore.user_exec_asce = mm->context.asce_bits | __pa(pgd);
diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index ddad5903341c..68940d0bad91 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -143,7 +143,8 @@ static inline pgd_t *pgd_alloc(struct mm_struct *mm)
         spin_lock_init(&mm->context.list_lock);
         INIT_LIST_HEAD(&mm->context.crst_list);
         INIT_LIST_HEAD(&mm->context.pgtable_list);
-        return (pgd_t *) crst_table_alloc(mm, s390_noexec);
+        return (pgd_t *)
+                crst_table_alloc(mm, user_mode == SECONDARY_SPACE_MODE);
 }
 #define pgd_free(mm, pgd) crst_table_free(mm, (unsigned long *) pgd)
 
diff --git a/arch/s390/include/asm/setup.h b/arch/s390/include/asm/setup.h
index e37478e87286..52a779c337e8 100644
--- a/arch/s390/include/asm/setup.h
+++ b/arch/s390/include/asm/setup.h
@@ -49,17 +49,12 @@ extern unsigned long memory_end;
 
 void detect_memory_layout(struct mem_chunk chunk[]);
 
-#ifdef CONFIG_S390_SWITCH_AMODE
-extern unsigned int switch_amode;
-#else
-#define switch_amode    (0)
-#endif
-
-#ifdef CONFIG_S390_EXEC_PROTECT
-extern unsigned int s390_noexec;
-#else
-#define s390_noexec     (0)
-#endif
+#define PRIMARY_SPACE_MODE      0
+#define ACCESS_REGISTER_MODE    1
+#define SECONDARY_SPACE_MODE    2
+#define HOME_SPACE_MODE         3
+
+extern unsigned int user_mode;
 
 /*
  * Machine features detected in head.S