1 files changed, 41 insertions, 19 deletions

diff --git a/arch/s390/include/asm/facility.h b/arch/s390/include/asm/facility.h
index 796007125dff..5f5b1aa6c233 100644
--- a/arch/s390/include/asm/facility.h
+++ b/arch/s390/include/asm/facility.h
@@ -14,13 +14,12 @@
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/preempt.h>
-
+#include <asm/alternative.h>
 #include <asm/lowcore.h>
 
 #define MAX_FACILITY_BIT (sizeof(stfle_fac_list) * 8)
 
 extern u64 stfle_fac_list[16];
-extern u64 alt_stfle_fac_list[16];
 
 static inline void __set_facility(unsigned long nr, void *facilities)
 {
@@ -40,33 +39,56 @@ static inline void __clear_facility(unsigned long nr, void *facilities)
 	ptr[nr >> 3] &= ~(0x80 >> (nr & 7));
 }
 
-static inline int __test_facility(unsigned long nr, void *facilities)
+static __always_inline bool __test_facility(unsigned long nr, void *facilities)
 {
 	unsigned char *ptr;
 
 	if (nr >= MAX_FACILITY_BIT)
-		return 0;
+		return false;
 	ptr = (unsigned char *) facilities + (nr >> 3);
 	return (*ptr & (0x80 >> (nr & 7))) != 0;
 }
 
 /*
+ * __test_facility_constant() generates a single instruction branch. If the
+ * tested facility is available (likely) the branch is patched into a nop.
+ *
+ * Do not use this function unless you know what you are doing. All users are
+ * supposed to use test_facility() which will do the right thing.
+ */
+static __always_inline bool __test_facility_constant(unsigned long nr)
+{
+	asm goto(
+		ALTERNATIVE("brcl 15,%l[l_no]", "brcl 0,0", ALT_FACILITY(%[nr]))
+		:
+		: [nr] "i" (nr)
+		:
+		: l_no);
+	return true;
+l_no:
+	return false;
+}
+
+/*
  * The test_facility function uses the bit ordering where the MSB is bit 0.
  * That makes it easier to query facility bits with the bit number as
  * documented in the Principles of Operation.
  */
-static inline int test_facility(unsigned long nr)
+static __always_inline bool test_facility(unsigned long nr)
 {
 	unsigned long facilities_als[] = { FACILITIES_ALS };
 
-	if (__builtin_constant_p(nr) && nr < sizeof(facilities_als) * 8) {
-		if (__test_facility(nr, &facilities_als))
-			return 1;
+	if (!__is_defined(__DECOMPRESSOR) && __builtin_constant_p(nr)) {
+		if (nr < sizeof(facilities_als) * 8) {
+			if (__test_facility(nr, &facilities_als))
+				return true;
+		}
+		return __test_facility_constant(nr);
 	}
 	return __test_facility(nr, &stfle_fac_list);
 }
 
-static inline unsigned long __stfle_asm(u64 *stfle_fac_list, int size)
+static inline unsigned long __stfle_asm(u64 *fac_list, int size)
 {
 	unsigned long reg0 = size - 1;
 
@@ -74,7 +96,7 @@ static inline unsigned long __stfle_asm(u64 *stfle_fac_list, int size)
 		"	lgr	0,%[reg0]\n"
 		"	.insn	s,0xb2b00000,%[list]\n" /* stfle */
 		"	lgr	%[reg0],0\n"
-		: [reg0] "+&d" (reg0), [list] "+Q" (*stfle_fac_list)
+		: [reg0] "+&d" (reg0), [list] "+Q" (*fac_list)
 		:
 		: "memory", "cc", "0");
 	return reg0;
@@ -82,32 +104,32 @@ static inline unsigned long __stfle_asm(u64 *stfle_fac_list, int size)
 
 /**
  * stfle - Store facility list extended
- * @stfle_fac_list: array where facility list can be stored
+ * @fac_list: array where facility list can be stored
  * @size: size of passed in array in double words
  */
-static inline void __stfle(u64 *stfle_fac_list, int size)
+static inline void __stfle(u64 *fac_list, int size)
 {
 	unsigned long nr;
 	u32 stfl_fac_list;
 
 	asm volatile(
 		"	stfl	0(0)\n"
-		: "=m" (S390_lowcore.stfl_fac_list));
-	stfl_fac_list = S390_lowcore.stfl_fac_list;
-	memcpy(stfle_fac_list, &stfl_fac_list, 4);
+		: "=m" (get_lowcore()->stfl_fac_list));
+	stfl_fac_list = get_lowcore()->stfl_fac_list;
+	memcpy(fac_list, &stfl_fac_list, 4);
 	nr = 4; /* bytes stored by stfl */
 	if (stfl_fac_list & 0x01000000) {
 		/* More facility bits available with stfle */
-		nr = __stfle_asm(stfle_fac_list, size);
+		nr = __stfle_asm(fac_list, size);
 		nr = min_t(unsigned long, (nr + 1) * 8, size * 8);
 	}
-	memset((char *) stfle_fac_list + nr, 0, size * 8 - nr);
+	memset((char *)fac_list + nr, 0, size * 8 - nr);
 }
 
-static inline void stfle(u64 *stfle_fac_list, int size)
+static inline void stfle(u64 *fac_list, int size)
 {
 	preempt_disable();
-	__stfle(stfle_fac_list, size);
+	__stfle(fac_list, size);
 	preempt_enable();
 }