[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>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 3df5b918cfe..77108e34fc1 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -112,7 +112,7 @@ static inline int user_space_fault(unsigned long trans_exc_code)
         if (trans_exc_code == 2)
                 /* Access via secondary space, set_fs setting decides */
                 return current->thread.mm_segment.ar4;
-        if (!switch_amode)
+        if (user_mode == HOME_SPACE_MODE)
                 /* User space if the access has been done via home space. */
                 return trans_exc_code == 3;
         /*
@@ -168,7 +168,7 @@ static void do_no_context(struct pt_regs *regs, unsigned long error_code,
          * terminate things with extreme prejudice.
          */
         address = trans_exc_code & __FAIL_ADDR_MASK;
-        if (user_space_fault(trans_exc_code) == 0)
+        if (!user_space_fault(trans_exc_code))
                 printk(KERN_ALERT "Unable to handle kernel pointer dereference"
                        " at virtual kernel address %p\n", (void *)address);
         else