1/*
2 * Copyright (c) 1999-2007 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28/* Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.
29 *
30 *	File:	libc/ppc/sys/vfork.s
31 *
32 * HISTORY
33 * 23-Jun-1998	Umesh Vaishampayan (umeshv@apple.com)
34 *	Created from fork.s
35 *
36 */
37
38#include "SYS.h"
39
40#if defined(__i386__)
41
42#if defined(__DYNAMIC__)
43#define GET_CURRENT_PID	PICIFY(__current_pid)
44
45        NON_LAZY_STUB(__current_pid)
46#define __current_pid	(%edx)
47#else
48#define GET_CURRENT_PID
49#endif
50
51/*
52 * If __current_pid >= 0, we want to put a -1 in there
53 * otherwise we just decrement it
54 */
55
56LEAF(___vfork, 0)
57	GET_CURRENT_PID
58	movl		__current_pid, %eax
590:
60	xorl		%ecx, %ecx
61	testl		%eax, %eax
62	cmovs		%eax, %ecx
63	decl		%ecx
64	lock
65	cmpxchgl	%ecx, __current_pid
66	jne		0b
67	popl		%ecx
68	movl		$(SYS_vfork), %eax	// code for vfork -> eax
69	UNIX_SYSCALL_TRAP			// do the system call
70	jnb		L1                     	// jump if CF==0
71	GET_CURRENT_PID
72	lock
73	incl		__current_pid
74	pushl		%ecx
75	BRANCH_EXTERN(cerror)
76
77L1:
78	testl		%edx, %edx		// CF=OF=0,  ZF set if zero result
79	jz		L2			// parent, since r1 == 0 in parent, 1 in child
80	xorl		%eax, %eax		// zero eax
81	jmp		*%ecx
82
83L2:
84	GET_CURRENT_PID
85	lock
86	incl		__current_pid
87	jmp		*%ecx
88
89#elif defined(__x86_64__)
90
91/*
92 * If __current_pid >= 0, we want to put a -1 in there
93 * otherwise we just decrement it
94 */
95
96LEAF(___vfork, 0)
97	movq		__current_pid@GOTPCREL(%rip), %rax
98	movl		(%rax), %eax
990:
100	xorl		%ecx, %ecx
101	testl		%eax, %eax
102	cmovs		%eax, %ecx
103	subl		$1, %ecx
104	movq		__current_pid@GOTPCREL(%rip), %rdx
105	lock
106	cmpxchgl	%ecx, (%rdx)
107	jne		0b
108	popq		%rdi			// return address in %rdi
109	movq		$ SYSCALL_CONSTRUCT_UNIX(SYS_vfork), %rax	// code for vfork -> rax
110	UNIX_SYSCALL_TRAP			// do the system call
111	jnb		L1					// jump if CF==0
112	pushq		%rdi			// put return address back on stack for cerror
113	movq		__current_pid@GOTPCREL(%rip), %rcx
114	lock
115	addq		$1, (%rcx)
116	movq		(%rcx), %rdi
117	BRANCH_EXTERN(cerror)
118
119L1:
120	testl		%edx, %edx		// CF=OF=0,  ZF set if zero result
121	jz		L2			// parent, since r1 == 0 in parent, 1 in child
122	xorq		%rax, %rax		// zero rax
123	jmp		*%rdi
124
125L2:
126	movq		__current_pid@GOTPCREL(%rip), %rdx
127	lock
128	addq		$1, (%rdx)
129	jmp		*%rdi
130
131#elif defined(__arm__)
132
133#include <arm/arch.h>
134
135	.globl	cerror
136	MI_ENTRY_POINT(___vfork)
137
138	MI_GET_ADDRESS(r3, __current_pid)	// get address of __current_pid
139#ifdef _ARM_ARCH_6
140L0:
141	ldrex	r1, [r3]
142	subs	r1, r1, #1			// if __current_pid <= 0, decrement it
143	movpl	r1, #-1				// otherwise put -1 in there
144	strex	r2, r1, [r3]
145	cmp	r2, #0
146	bne	L0
147#else
148	mov	r2, #0x80000000			// load "looking" value
149L0:
150	swp	r1, r2, [r3]			// look at the value, lock others out
151	cmp	r1, r2				// anyone else trying to look?
152	beq	L0				// yes, so wait our turn
153        subs    r1, r1, #1                      // if __current_pid <= 0, decrement it
154	movpl   r1, #-1                         // otherwise put -1 in there
155	str	r1, [r3]
156#endif
157
158	mov	r1, #1					// prime results
159	mov	r12, #SYS_vfork
160	swi	#SWI_SYSCALL				// make the syscall
161	bcs	Lbotch					// error?
162	cmp	r1, #0					// parent (r1=0) or child(r1=1)
163	beq	Lparent
164
165	//child here...
166	mov	r0, #0
167	bx	lr					// return
168
169Lbotch:
170	MI_CALL_EXTERNAL(cerror)			// jump here on error
171	mov	r0,#-1					// set the error
172	// reload values clobbered by cerror (so we can treat them as live in Lparent)
173	MI_GET_ADDRESS(r3, __current_pid)		// get address of __current_pid
174#ifndef _ARM_ARCH_6
175	mov	r2, #0x80000000			// load "looking" value
176#endif
177	// fall thru
178
179Lparent:
180#ifdef _ARM_ARCH_6
181	ldrex	r1, [r3]
182	add	r1, r1, #1			// we're back, decrement vfork count
183	strex	r2, r1, [r3]
184	cmp	r2, #0
185	bne	Lparent
186#else
187	swp	r1, r2, [r3]			// look at the value, lock others out
188	cmp	r1, r2				// anyone else trying to look?
189	beq	Lparent				// yes, so wait our turn
190	add	r1, r1, #1			// we're back, decrement vfork count
191	str	r1, [r3]
192#endif
193
194	bx	lr					// return
195
196#else
197#error Unsupported architecture
198#endif
199