[S390] Convert machine feature detection code to C.

From: Heiko Carstens <heiko.carstens@de.ibm.com>
From: Carsten Otte <cotte@de.ibm.com>

This lets us use defines for the magic bits in machine flags instead
of using plain numbers all over the place.
In addition on newer machines features/facilities are indicated by the
result of the stfl instruction. So we use these bits instead of trying
to execute new instructions and check wether we get an exception or
not.
Also the mvpg instruction is always available when in zArch mode,
whereas the idte instruction is only available in zArch mode. This
results in some minor optimizations.

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

1 files changed, 8 insertions, 0 deletions

diff --git a/include/asm-s390/system.h b/include/asm-s390/system.h
index 79bdbf4b33a7..c819ae25a842 100644
--- a/include/asm-s390/system.h
+++ b/include/asm-s390/system.h
@@ -432,6 +432,14 @@ static inline unsigned int stfl(void)
 	return S390_lowcore.stfl_fac_list;
 }
 
+static inline unsigned short stap(void)
+{
+	unsigned short cpu_address;
+
+	asm volatile("stap %0" : "=m" (cpu_address));
+	return cpu_address;
+}
+
 extern void (*_machine_restart)(char *command);
 extern void (*_machine_halt)(void);
 extern void (*_machine_power_off)(void);