[S390] cleanup system call parameter setup

Do the setup of the stack overflow argument for the sixth system
call parameter right before the branch to the system call function.
That simplifies the system call parameter access code.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/syscall.h

@@ -65,8 +65,6 @@ static inline void syscall_get_arguments(struct task_struct *task,
 	if (test_tsk_thread_flag(task, TIF_31BIT))
 		mask = 0xffffffff;
 #endif
-	if (i + n == 6)
-		args[--n] = regs->args[0] & mask;
 	while (n-- > 0)
 		if (i + n > 0)
 			args[n] = regs->gprs[2 + i + n] & mask;
@@ -80,8 +78,6 @@ static inline void syscall_set_arguments(struct task_struct *task,
 					 const unsigned long *args)
 {
 	BUG_ON(i + n > 6);
-	if (i + n == 6)
-		regs->args[0] = args[--n];
 	while (n-- > 0)
 		if (i + n > 0)
 			regs->gprs[2 + i + n] = args[n];

arch/s390/kernel/entry.S

@@ -254,12 +254,11 @@ sysc_do_svc:
 	bnl	BASED(sysc_nr_ok)
 	lr	%r7,%r1 	  # copy svc number to %r7
 sysc_nr_ok:
-	mvc	SP_ARGS(4,%r15),SP_R7(%r15)
-sysc_do_restart:
 	sth	%r7,SP_SVCNR(%r15)
 	sll	%r7,2		  # svc number *4
 	l	%r8,BASED(.Lsysc_table)
 	tm	__TI_flags+2(%r9),_TIF_SYSCALL
+	mvc	SP_ARGS(4,%r15),SP_R7(%r15)
 	l	%r8,0(%r7,%r8)	  # get system call addr.
 	bnz	BASED(sysc_tracesys)
 	basr	%r14,%r8	  # call sys_xxxx
@@ -347,7 +346,7 @@ sysc_restart:
 	l	%r7,SP_R2(%r15) 	# load new svc number
 	mvc	SP_R2(4,%r15),SP_ORIG_R2(%r15) # restore first argument
 	lm	%r2,%r6,SP_R2(%r15)	# load svc arguments
-	b	BASED(sysc_do_restart)	# restart svc
+	b	BASED(sysc_nr_ok)	# restart svc
 
 #
 # _TIF_SINGLE_STEP is set, call do_single_step
@@ -380,6 +379,7 @@ sysc_tracesys:
 	l	%r8,0(%r7,%r8)
 sysc_tracego:
 	lm	%r3,%r6,SP_R3(%r15)
+	mvc	SP_ARGS(4,%r15),SP_R7(%r15)
 	l	%r2,SP_ORIG_R2(%r15)
 	basr	%r14,%r8		# call sys_xxx
 	st	%r2,SP_R2(%r15)		# store return value

arch/s390/kernel/entry64.S

@@ -246,7 +246,6 @@ sysc_saveall:
 	CREATE_STACK_FRAME __LC_SAVE_AREA
 	mvc	SP_PSW(16,%r15),__LC_SVC_OLD_PSW
 	mvc	SP_ILC(4,%r15),__LC_SVC_ILC
-	stg	%r7,SP_ARGS(%r15)
 	lg	%r12,__LC_THREAD_INFO	# load pointer to thread_info struct
 sysc_vtime:
 	UPDATE_VTIME __LC_EXIT_TIMER,__LC_SYNC_ENTER_TIMER,__LC_USER_TIMER
@@ -274,6 +273,7 @@ sysc_nr_ok:
 sysc_noemu:
 #endif
 	tm	__TI_flags+6(%r12),_TIF_SYSCALL
+	mvc	SP_ARGS(8,%r15),SP_R7(%r15)
 	lgf	%r8,0(%r7,%r10) # load address of system call routine
 	jnz	sysc_tracesys
 	basr	%r14,%r8	# call sys_xxxx
@@ -387,6 +387,7 @@ sysc_tracesys:
 	lgf	%r8,0(%r7,%r10)
 sysc_tracego:
 	lmg	%r3,%r6,SP_R3(%r15)
+	mvc	SP_ARGS(8,%r15),SP_R7(%r15)
 	lg	%r2,SP_ORIG_R2(%r15)
 	basr	%r14,%r8		# call sys_xxx
 	stg	%r2,SP_R2(%r15)		# store return value
@@ -953,7 +954,6 @@ cleanup_system_call:
 	CREATE_STACK_FRAME __LC_SAVE_AREA
 	mvc	SP_PSW(16,%r15),__LC_SVC_OLD_PSW
 	mvc	SP_ILC(4,%r15),__LC_SVC_ILC
-	stg	%r7,SP_ARGS(%r15)
 	mvc	8(8,%r12),__LC_THREAD_INFO
 cleanup_vtime:
 	clc	__LC_RETURN_PSW+8(8),BASED(cleanup_system_call_insn+24)