Commit 37fe5d41 authored by Al Viro's avatar Al Viro
Browse files

s390: fold kernel_thread_helper() into ret_from_fork() 



... and don't bother with syscall return path in case of kernel
threads.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 65f22a90

arch/s390/kernel/entry.S

+15 −3
Original line number Diff line number Diff line
@@ -331,14 +331,26 @@ ENTRY(ret_from_fork) 
	l	%r12,__LC_THREAD_INFO

	l	%r13,__LC_SVC_NEW_PSW+4

	tm	__PT_PSW+1(%r11),0x01	# forking a kernel thread ?

	jo	0f

	st	%r15,__PT_R15(%r11)	# store stack pointer for new kthread

0:	l	%r1,BASED(.Lschedule_tail)

	je	1f

	l	%r1,BASED(.Lschedule_tail)

	basr	%r14,%r1		# call schedule_tail

	TRACE_IRQS_ON

	ssm	__LC_SVC_NEW_PSW	# reenable interrupts

	j	sysc_tracenogo



1:	# it's a kernel thread

	st	%r15,__PT_R15(%r11)	# store stack pointer for new kthread

	l	%r1,BASED(.Lschedule_tail)

	basr	%r14,%r1		# call schedule_tail

	TRACE_IRQS_ON

	ssm	__LC_SVC_NEW_PSW	# reenable interrupts

	lm	%r9,%r11,__PT_R9(%r11)	# load gprs

ENTRY(kernel_thread_starter)

	la	%r2,0(%r10)

	basr	%r14,%r9

	la	%r2,0

	br	%r11			# do_exit



#

# kernel_execve function needs to deal with pt_regs that is not

# at the usual place

arch/s390/kernel/entry64.S

+13 −3
Original line number Diff line number Diff line
@@ -352,12 +352,22 @@ ENTRY(ret_from_fork) 
	la	%r11,STACK_FRAME_OVERHEAD(%r15)

	lg	%r12,__LC_THREAD_INFO

	tm	__PT_PSW+1(%r11),0x01	# forking a kernel thread ?

	jo	0f

	stg	%r15,__PT_R15(%r11)	# store stack pointer for new kthread

0:	brasl	%r14,schedule_tail

	je	1f

	brasl	%r14,schedule_tail

	TRACE_IRQS_ON

	ssm	__LC_SVC_NEW_PSW	# reenable interrupts

	j	sysc_tracenogo

1:	# it's a kernel thread

	stg	%r15,__PT_R15(%r11)	# store stack pointer for new kthread

	brasl	%r14,schedule_tail

	TRACE_IRQS_ON

	ssm	__LC_SVC_NEW_PSW	# reenable interrupts

	lmg	%r9,%r11,__PT_R9(%r11)	# load gprs

ENTRY(kernel_thread_starter)

	la	%r2,0(%r10)

	basr	%r14,%r9

	la	%r2,0

	br	%r11			# do_exit



#

# kernel_execve function needs to deal with pt_regs that is not

arch/s390/kernel/process.c

+0 −10
Original line number Diff line number Diff line
@@ -98,16 +98,6 @@ void cpu_idle(void) 


extern void __kprobes kernel_thread_starter(void);



asm(

	".section .kprobes.text, \"ax\"\n"

	".global kernel_thread_starter\n"

	"kernel_thread_starter:\n"

	"    la    2,0(10)\n"

	"    basr  14,9\n"

	"    la    2,0\n"

	"    br    11\n"

	".previous\n");



int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)

{

	struct pt_regs regs;