[S390] missing sacf in uaccess

The uaccess functions copy_in_user_std and clear_user_std fail to
switch back from secondary space mode to primary space mode with sacf
in case of an unresolvable page fault. We need to make sure that the
switch back to primary mode is done in all cases, otherwise the code
following the uaccess inline assembly will crash.

Reported-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/lib/uaccess_std.c

@@ -125,9 +125,9 @@ static size_t copy_in_user_std(size_t size, void __user *to,
 	unsigned long tmp1;
 
 	asm volatile(
+		"   sacf  256\n"
 		"  "AHI"  %0,-1\n"
 		"   jo    5f\n"
-		"   sacf  256\n"
 		"   bras  %3,3f\n"
 		"0:"AHI"  %0,257\n"
 		"1: mvc   0(1,%1),0(%2)\n"
@@ -142,9 +142,8 @@ static size_t copy_in_user_std(size_t size, void __user *to,
 		"3:"AHI"  %0,-256\n"
 		"   jnm   2b\n"
 		"4: ex    %0,1b-0b(%3)\n"
-		"   sacf  0\n"
 		"5: "SLR"  %0,%0\n"
-		"6:\n"
+		"6: sacf  0\n"
 		EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
 		: "+a" (size), "+a" (to), "+a" (from), "=a" (tmp1)
 		: : "cc", "memory");
@@ -156,9 +155,9 @@ static size_t clear_user_std(size_t size, void __user *to)
 	unsigned long tmp1, tmp2;
 
 	asm volatile(
+		"   sacf  256\n"
 		"  "AHI"  %0,-1\n"
 		"   jo    5f\n"
-		"   sacf  256\n"
 		"   bras  %3,3f\n"
 		"   xc    0(1,%1),0(%1)\n"
 		"0:"AHI"  %0,257\n"
@@ -178,9 +177,8 @@ static size_t clear_user_std(size_t size, void __user *to)
 		"3:"AHI"  %0,-256\n"
 		"   jnm   2b\n"
 		"4: ex    %0,0(%3)\n"
-		"   sacf  0\n"
 		"5: "SLR"  %0,%0\n"
-		"6:\n"
+		"6: sacf  0\n"
 		EX_TABLE(1b,6b) EX_TABLE(2b,0b) EX_TABLE(4b,0b)
 		: "+a" (size), "+a" (to), "=a" (tmp1), "=a" (tmp2)
 		: : "cc", "memory");