From: Carsten Otte <cotte@de.ibm.com>
Date: Thu, 26 Mar 2009 14:23:57 +0000 (+0100)
Subject: [S390] check addressing mode in s390_enable_sie
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=702d9e584feb028ed7e2a6d2b103b8ea57622ff2;p=linux-beck.git

[S390] check addressing mode in s390_enable_sie

The sie instruction requires address spaces to be switched
to run proper. This patch verifies that this is the case
in s390_enable_sie, otherwise the kernel would crash badly
as soon as the process runs into sie.

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

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 6b6ddc4ea02b..9bf86125f6f3 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -258,6 +258,10 @@ int s390_enable_sie(void)
 	struct task_struct *tsk = current;
 	struct mm_struct *mm, *old_mm;
 
+	/* Do we have switched amode? If no, we cannot do sie */
+	if (!switch_amode)
+		return -EINVAL;
+
 	/* Do we have pgstes? if yes, we are done */
 	if (tsk->mm->context.has_pgste)
 		return 0;