s390/lpp: use assembler alternatives for the LPP instruction

With the new macros for CPU alternatives the MACHINE_FLAG_LPP check
around the LPP instruction can be optimized. After this is done the
flag can be removed.

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

arch/s390/kernel/early.c

@@ -242,8 +242,6 @@ static __init void detect_machine_facilities(void)
 		S390_lowcore.machine_flags |= MACHINE_FLAG_EDAT2;
 	if (test_facility(3))
 		S390_lowcore.machine_flags |= MACHINE_FLAG_IDTE;
-	if (test_facility(40))
-		S390_lowcore.machine_flags |= MACHINE_FLAG_LPP;
 	if (test_facility(50) && test_facility(73)) {
 		S390_lowcore.machine_flags |= MACHINE_FLAG_TE;
 		__ctl_set_bit(0, 55);

arch/s390/kernel/entry.S

@@ -58,6 +58,8 @@ _CIF_WORK	= (_CIF_MCCK_PENDING | _CIF_ASCE_PRIMARY | \
 		   _CIF_ASCE_SECONDARY | _CIF_FPU)
 _PIF_WORK	= (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART)
 
+_LPP_OFFSET	= __LC_LPP
+
 #define BASED(name) name-cleanup_critical(%r13)
 
 	.macro	TRACE_IRQS_ON
@@ -281,10 +283,8 @@ ENTRY(__switch_to)
 	aghi	%r3,__TASK_pid
 	mvc	__LC_CURRENT_PID(4,%r0),0(%r3)	# store pid of next
 	lmg	%r6,%r15,__SF_GPRS(%r15)	# load gprs of next task
-	TSTMSK	__LC_MACHINE_FLAGS,MACHINE_FLAG_LPP
-	jz	0f
-	.insn	s,0xb2800000,__LC_LPP		# set program parameter
-0:	BR_R1USE_R14
+	ALTERNATIVE "", ".insn s,0xb2800000,_LPP_OFFSET", 40
+	BR_R1USE_R14
 
 .L__critical_start:
 
@@ -1243,10 +1243,8 @@ ENTRY(mcck_int_handler)
 # PSW restart interrupt handler
 #
 ENTRY(restart_int_handler)
-	TSTMSK	__LC_MACHINE_FLAGS,MACHINE_FLAG_LPP
-	jz	0f
-	.insn	s,0xb2800000,__LC_LPP
-0:	stg	%r15,__LC_SAVE_AREA_RESTART
+	ALTERNATIVE "", ".insn s,0xb2800000,_LPP_OFFSET", 40
+	stg	%r15,__LC_SAVE_AREA_RESTART
 	lg	%r15,__LC_RESTART_STACK
 	aghi	%r15,-__PT_SIZE			# create pt_regs on stack
 	xc	0(__PT_SIZE,%r15),0(%r15)