1/* kernel_thread.S: kernel thread creation
 2 *
 3 * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
 4 * Written by David Howells (dhowells@redhat.com)
 5 *
 6 * This program is free software; you can redistribute it and/or
 7 * modify it under the terms of the GNU General Public License
 8 * as published by the Free Software Foundation; either version
 9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/linkage.h>
13#include <asm/unistd.h>
14
15#define CLONE_VM	0x00000100	/* set if VM shared between processes */
16#define	KERN_ERR	"<3>"
17
18	.section .rodata
19kernel_thread_emsg:
20	.asciz	KERN_ERR "failed to create kernel thread: error=%d\n"
21
22	.text
23	.balign		4
24
25###############################################################################
26#
27# Create a kernel thread
28#
29# int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
30#
31###############################################################################
32	.globl		kernel_thread
33	.type		kernel_thread,@function
34kernel_thread:
35	or.p		gr8,gr0,gr4
36	or		gr9,gr0,gr5
37
38	# start by forking the current process, but with shared VM
39	setlos.p	#__NR_clone,gr7		; syscall number
40	ori		gr10,#CLONE_VM,gr8	; first syscall arg	[clone_flags]
41	sethi.p		#0xe4e4,gr9		; second syscall arg	[newsp]
42	setlo		#0xe4e4,gr9
43	setlos.p	#0,gr10			; third syscall arg	[parent_tidptr]
44	setlos		#0,gr11			; fourth syscall arg	[child_tidptr]
45	tira		gr0,#0
46	setlos.p	#4095,gr7
47	andcc		gr8,gr8,gr0,icc0
48	addcc.p		gr8,gr7,gr0,icc1
49	bnelr		icc0,#2
50	bc		icc1,#0,kernel_thread_error
51
52	# now invoke the work function
53	or		gr5,gr0,gr8
54	calll		@(gr4,gr0)
55
56	# and finally exit the thread
57	setlos		#__NR_exit,gr7		; syscall number
58	tira		gr0,#0
59
60kernel_thread_error:
61	subi		sp,#8,sp
62	movsg		lr,gr4
63	sti		gr8,@(sp,#0)
64	sti.p		gr4,@(sp,#4)
65
66	or		gr8,gr0,gr9
67	sethi.p		%hi(kernel_thread_emsg),gr8
68	setlo		%lo(kernel_thread_emsg),gr8
69
70	call		printk
71
72	ldi		@(sp,#4),gr4
73	ldi		@(sp,#0),gr8
74	subi		sp,#8,sp
75	jmpl		@(gr4,gr0)
76
77	.size		kernel_thread,.-kernel_thread