[S390] System call cleanup.

Remove system call glue for sys_clone, sys_fork, sys_vfork, sys_execve,
sys_sigreturn, sys_rt_sigreturn and sys_sigaltstack. Call do_execve from
kernel_execve directly, move pt_regs to the right place and branch to
sysc_return to start the user space program. This removes the last
in-kernel system call.

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

1 files changed, 32 insertions, 55 deletions

diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index dddc3de3040..c8a2212014e 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -249,8 +249,6 @@ sysc_do_restart:
 	bnz	BASED(sysc_tracesys)
 	basr	%r14,%r8	  # call sys_xxxx
 	st	%r2,SP_R2(%r15)   # store return value (change R2 on stack)
-				  # ATTENTION: check sys_execve_glue before
-				  # changing anything here !!
 
 sysc_return:
 	tm	SP_PSW+1(%r15),0x01	# returning to user ?
@@ -381,50 +379,37 @@ ret_from_fork:
 	b	BASED(sysc_return)
 
 #
-# clone, fork, vfork, exec and sigreturn need glue,
-# because they all expect pt_regs as parameter,
-# but are called with different parameter.
-# return-address is set up above
+# kernel_execve function needs to deal with pt_regs that is not
+# at the usual place
 #
-sys_clone_glue:
-	la	%r2,SP_PTREGS(%r15)	# load pt_regs
-	l	%r1,BASED(.Lclone)
-	br	%r1			# branch to sys_clone
-
-sys_fork_glue:
-	la	%r2,SP_PTREGS(%r15)	# load pt_regs
-	l	%r1,BASED(.Lfork)
-	br	%r1			# branch to sys_fork
-
-sys_vfork_glue:
-	la	%r2,SP_PTREGS(%r15)	# load pt_regs
-	l	%r1,BASED(.Lvfork)
-	br	%r1			# branch to sys_vfork
-
-sys_execve_glue:
-	la	%r2,SP_PTREGS(%r15)	# load pt_regs
-	l	%r1,BASED(.Lexecve)
-	lr	%r12,%r14		# save return address
-	basr	%r14,%r1		# call sys_execve
-	ltr	%r2,%r2			# check if execve failed
-	bnz	0(%r12)			# it did fail -> store result in gpr2
-	b	4(%r12)			# SKIP ST 2,SP_R2(15) after BASR 14,8
-					# in system_call/sysc_tracesys
-
-sys_sigreturn_glue:
-	la	%r2,SP_PTREGS(%r15)	# load pt_regs as parameter
-	l	%r1,BASED(.Lsigreturn)
-	br	%r1			# branch to sys_sigreturn
-
-sys_rt_sigreturn_glue:
-	la	%r2,SP_PTREGS(%r15)	# load pt_regs as parameter
-	l	%r1,BASED(.Lrt_sigreturn)
-	br	%r1			# branch to sys_sigreturn
-
-sys_sigaltstack_glue:
-	la	%r4,SP_PTREGS(%r15)	# load pt_regs as parameter
-	l	%r1,BASED(.Lsigaltstack)
-	br	%r1			# branch to sys_sigreturn
+	.globl	kernel_execve
+kernel_execve:
+	stm	%r12,%r15,48(%r15)
+	lr	%r14,%r15
+	l	%r13,__LC_SVC_NEW_PSW+4
+	s	%r15,BASED(.Lc_spsize)
+	st	%r14,__SF_BACKCHAIN(%r15)
+	la	%r12,SP_PTREGS(%r15)
+	xc	0(__PT_SIZE,%r12),0(%r12)
+	l	%r1,BASED(.Ldo_execve)
+	lr	%r5,%r12
+	basr	%r14,%r1
+	ltr	%r2,%r2
+	be	BASED(0f)
+	a	%r15,BASED(.Lc_spsize)
+	lm	%r12,%r15,48(%r15)
+	br	%r14
+	# execve succeeded.
+0:	stnsm	__SF_EMPTY(%r15),0xfc	# disable interrupts
+	l	%r15,__LC_KERNEL_STACK	# load ksp
+	s	%r15,BASED(.Lc_spsize)	# make room for registers & psw
+	l	%r9,__LC_THREAD_INFO
+	mvc	SP_PTREGS(__PT_SIZE,%r15),0(%r12)	# copy pt_regs
+	xc	__SF_BACKCHAIN(4,%r15),__SF_BACKCHAIN(%r15)
+	stosm	__SF_EMPTY(%r15),0x03	# reenable interrupts
+	l	%r1,BASED(.Lexecve_tail)
+	basr	%r14,%r1
+	b	BASED(sysc_return)
 
 /*
  * Program check handler routine
@@ -1031,19 +1016,11 @@ cleanup_io_leave_insn:
 .Ldo_extint:	.long	do_extint
 .Ldo_signal:	.long	do_signal
 .Lhandle_per:	.long	do_single_step
+.Ldo_execve:	.long	do_execve
+.Lexecve_tail:	.long	execve_tail
 .Ljump_table:	.long	pgm_check_table
 .Lschedule:	.long	schedule
-.Lclone:	.long	sys_clone
-.Lexecve:	.long	sys_execve
-.Lfork: 	.long	sys_fork
-.Lrt_sigreturn: .long	sys_rt_sigreturn
-.Lrt_sigsuspend:
-		.long	sys_rt_sigsuspend
-.Lsigreturn:	.long	sys_sigreturn
-.Lsigsuspend:	.long	sys_sigsuspend
-.Lsigaltstack:	.long	sys_sigaltstack
 .Ltrace:	.long	syscall_trace
-.Lvfork:	.long	sys_vfork
 .Lschedtail:	.long	schedule_tail
 .Lsysc_table:	.long	sys_call_table
 #ifdef CONFIG_TRACE_IRQFLAGS