From: Heiko Carstens <heiko.carstens@de.ibm.com>
Date: Tue, 24 Nov 2015 12:48:27 +0000 (+0100)
Subject: s390/facilities: optimize test_facility()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=6ab6c31a5450b73133e04c3976469d6d72f55df3;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

s390/facilities: optimize test_facility()

test_facility() can be optimized for bits which must be set anyway,
due to the check in head.S. This removes a couple of superfluous
runtime checks.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---

diff --git a/arch/s390/include/asm/facility.h b/arch/s390/include/asm/facility.h
index 007163f91856..09b406db7529 100644
--- a/arch/s390/include/asm/facility.h
+++ b/arch/s390/include/asm/facility.h
@@ -34,6 +34,12 @@ static inline int __test_facility(unsigned long nr, void *facilities)
  */
 static inline int 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;
+	}
 	return __test_facility(nr, &S390_lowcore.stfle_fac_list);
 }