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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: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-09-10 18:03:41 -04:00
parent 65f22a906e
commit 37fe5d41f6
3 changed files with 28 additions and 16 deletions
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18
arch/s390/kernel/entry.S
View File

@ -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

16
arch/s390/kernel/entry64.S
View File

@ -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

10
arch/s390/kernel/process.c
View File

@ -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;