s390/uaccess: avoid mvcos jump label

If the kernel is compiled for z10 or later machines the uaccess
code inlines the mvcos instruction. The facility bit 27 which
indicates the availability of MVCOS has to be set. The have_mvcos
jump label will always be true.

Make the generation of the have_mvcos jump label conditional on
!CONFIG_HAVE_MARCH_Z10_FEATURES.

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

diff --git a/arch/s390/lib/uaccess.c b/arch/s390/lib/uaccess.c
index b3bd3f23b8e851c7f67e46cb527e20603512e7f5..4ea9106417ee0f177df50a6187c6e2436972f4ca 100644 (file)
--- a/arch/s390/lib/uaccess.c
+++ b/arch/s390/lib/uaccess.c
@@ -15,8 +15,30 @@
 #include <asm/mmu_context.h>
 #include <asm/facility.h>
 
+#ifndef CONFIG_HAVE_MARCH_Z10_FEATURES
 static DEFINE_STATIC_KEY_FALSE(have_mvcos);
 
+static int __init uaccess_init(void)
+{
+       if (test_facility(27))
+               static_branch_enable(&have_mvcos);
+       return 0;
+}
+early_initcall(uaccess_init);
+
+static inline int copy_with_mvcos(void)
+{
+       if (static_branch_likely(&have_mvcos))
+               return 1;
+       return 0;
+}
+#else
+static inline int copy_with_mvcos(void)
+{
+       return 1;
+}
+#endif
+
 static inline unsigned long copy_from_user_mvcos(void *x, const void __user *ptr,
                                                 unsigned long size)
 {
@@ -84,7 +106,7 @@ static inline unsigned long copy_from_user_mvcp(void *x, const void __user *ptr,
 
 unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-       if (static_branch_likely(&have_mvcos))
+       if (copy_with_mvcos())
                return copy_from_user_mvcos(to, from, n);
        return copy_from_user_mvcp(to, from, n);
 }
@@ -157,7 +179,7 @@ static inline unsigned long copy_to_user_mvcs(void __user *ptr, const void *x,
 
 unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 {
-       if (static_branch_likely(&have_mvcos))
+       if (copy_with_mvcos())
                return copy_to_user_mvcos(to, from, n);
        return copy_to_user_mvcs(to, from, n);
 }
@@ -220,7 +242,7 @@ static inline unsigned long copy_in_user_mvc(void __user *to, const void __user
 
 unsigned long raw_copy_in_user(void __user *to, const void __user *from, unsigned long n)
 {
-       if (static_branch_likely(&have_mvcos))
+       if (copy_with_mvcos())
                return copy_in_user_mvcos(to, from, n);
        return copy_in_user_mvc(to, from, n);
 }
@@ -292,7 +314,7 @@ static inline unsigned long clear_user_xc(void __user *to, unsigned long size)
 
 unsigned long __clear_user(void __user *to, unsigned long size)
 {
-       if (static_branch_likely(&have_mvcos))
+       if (copy_with_mvcos())
                        return clear_user_mvcos(to, size);
        return clear_user_xc(to, size);
 }
@@ -349,11 +371,3 @@ long __strncpy_from_user(char *dst, const char __user *src, long size)
        return done;
 }
 EXPORT_SYMBOL(__strncpy_from_user);
-
-static int __init uaccess_init(void)
-{
-       if (test_facility(27))
-               static_branch_enable(&have_mvcos);
-       return 0;
-}
-early_initcall(uaccess_init);