s390/alternative: use a copy of the facility bit mask

To be able to switch off specific CPU alternatives with kernel parameters
make a copy of the facility bit mask provided by STFLE and use the copy
for the decision to apply an alternative.

Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/arch/s390/include/asm/facility.h b/arch/s390/include/asm/facility.h
index fbe0c4be3cd8..99c8ce30b3cd 100644
--- a/arch/s390/include/asm/facility.h
+++ b/arch/s390/include/asm/facility.h
@@ -15,6 +15,24 @@
 
 #define MAX_FACILITY_BIT (sizeof(((struct lowcore *)0)->stfle_fac_list) * 8)
 
+static inline void __set_facility(unsigned long nr, void *facilities)
+{
+	unsigned char *ptr = (unsigned char *) facilities;
+
+	if (nr >= MAX_FACILITY_BIT)
+		return;
+	ptr[nr >> 3] |= 0x80 >> (nr & 7);
+}
+
+static inline void __clear_facility(unsigned long nr, void *facilities)
+{
+	unsigned char *ptr = (unsigned char *) facilities;
+
+	if (nr >= MAX_FACILITY_BIT)
+		return;
+	ptr[nr >> 3] &= ~(0x80 >> (nr & 7));
+}
+
 static inline int __test_facility(unsigned long nr, void *facilities)
 {
 	unsigned char *ptr;