[apple/xnu.git] / libsyscall / custom / __vfork.s

/*
 * Copyright (c) 1999-2007 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1998 Apple Computer, Inc.  All rights reserved.
 *
 *	File:	libc/ppc/sys/vfork.s
 *
 * HISTORY
 * 23-Jun-1998	Umesh Vaishampayan (umeshv@apple.com)
 *	Created from fork.s
 *
 */

#include "SYS.h"

#if defined(__ppc__) || defined(__ppc64__)

/* We use mode-independent "g" opcodes such as "srgi", and/or
 * mode-independent macros such as MI_GET_ADDRESS.  These expand
 * into word operations when targeting __ppc__, and into doubleword
 * operations when targeting __ppc64__.
 */
#include <architecture/ppc/mode_independent_asm.h>

/* In vfork(), the child runs in parent's address space.  */


MI_ENTRY_POINT(___vfork)
    MI_GET_ADDRESS(r5,__current_pid)  // get address of __current_pid in r5
2:
	lwarx	r6,0,r5			// don't cache pid across vfork
	cmpwi	r6,0
	ble--	3f              // is another vfork in progress
	li      r6,0			// if not, erase the stored pid
3:	
	addi	r6,r6,-1		// count the parallel vforks in
	stwcx.	r6,0,r5			// negative cached pid values
	bne--	2b
	
	li      r0,SYS_vfork
	sc
	b       Lbotch			// error return

	cmpwi	r4,0
	beq     Lparent			// parent, since a1 == 0 in parent,

	li      r3,0			// child
	blr

Lparent:                    // r3 == child's pid
	lwarx	r6,0,r5			// we're back, decrement vfork count
	addi	r6,r6,1
	stwcx.	r6,0,r5
	bne--	Lparent
	blr                     // return pid

Lbotch:
	lwarx	r6,0,r5			// never went, decrement vfork count
	addi	r6,r6,1
	stwcx.	r6,0,r5
	bne--	Lbotch

	MI_BRANCH_EXTERNAL(cerror)

#elif defined(__i386__)

#if defined(__DYNAMIC__)
#define GET_CURRENT_PID	PICIFY(__current_pid)

        NON_LAZY_STUB(__current_pid)
#define __current_pid	(%edx)
#else
#define GET_CURRENT_PID
#endif

/*
 * If __current_pid >= 0, we want to put a -1 in there
 * otherwise we just decrement it
 */

LEAF(___vfork, 0)
	GET_CURRENT_PID
	movl		__current_pid, %eax
0:
	xorl		%ecx, %ecx
	testl		%eax, %eax
	cmovs		%eax, %ecx
	decl		%ecx
	lock
	cmpxchgl	%ecx, __current_pid
	jne		0b
	popl		%ecx
	movl		$(SYS_vfork), %eax	// code for vfork -> eax
	UNIX_SYSCALL_TRAP			// do the system call
	jnb		L1                     	// jump if CF==0
	GET_CURRENT_PID
	lock
	incl		__current_pid
	pushl		%ecx
	BRANCH_EXTERN(cerror)

L1:
	testl		%edx, %edx		// CF=OF=0,  ZF set if zero result
	jz		L2			// parent, since r1 == 0 in parent, 1 in child
	xorl		%eax, %eax		// zero eax
	jmp		*%ecx

L2:
	GET_CURRENT_PID
	lock
	incl		__current_pid
	jmp		*%ecx

#elif defined(__x86_64__)

/*
 * If __current_pid >= 0, we want to put a -1 in there
 * otherwise we just decrement it
 */

LEAF(___vfork, 0)
	movq		__current_pid@GOTPCREL(%rip), %rax
	movl		(%rax), %eax
0:
	xorl		%ecx, %ecx
	testl		%eax, %eax
	cmovs		%eax, %ecx
	subl		$1, %ecx
	movq		__current_pid@GOTPCREL(%rip), %rdx
	lock
	cmpxchgl	%ecx, (%rdx)
	jne		0b
	popq		%rdi			// return address in %rdi
	movq		$ SYSCALL_CONSTRUCT_UNIX(SYS_vfork), %rax	// code for vfork -> rax
	UNIX_SYSCALL_TRAP			// do the system call
	jnb		L1					// jump if CF==0
	movq		__current_pid@GOTPCREL(%rip), %rcx
	lock
	addq		$1, (%rcx)
	movq		(%rcx), %rdi
	BRANCH_EXTERN(cerror)

L1:
	testl		%edx, %edx		// CF=OF=0,  ZF set if zero result
	jz		L2			// parent, since r1 == 0 in parent, 1 in child
	xorq		%rax, %rax		// zero rax
	jmp		*%rdi

L2:
	movq		__current_pid@GOTPCREL(%rip), %rdx
	lock
	addq		$1, (%rdx)
	jmp		*%rdi

#else
#error Unsupported architecture
#endif
Commit	Line	Data
2d21ac55 A	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(__ppc__) \|\| defined(__ppc64__)
	41
	42	/* We use mode-independent "g" opcodes such as "srgi", and/or
	43	* mode-independent macros such as MI_GET_ADDRESS. These expand
	44	* into word operations when targeting __ppc__, and into doubleword
	45	* operations when targeting __ppc64__.
	46	*/
	47	#include <architecture/ppc/mode_independent_asm.h>
	48
	49	/* In vfork(), the child runs in parent's address space. */
	50
	51
	52	MI_ENTRY_POINT(___vfork)
	53	MI_GET_ADDRESS(r5,__current_pid) // get address of __current_pid in r5
	54	2:
	55	lwarx r6,0,r5 // don't cache pid across vfork
	56	cmpwi r6,0
	57	ble-- 3f // is another vfork in progress
	58	li r6,0 // if not, erase the stored pid
	59	3:
	60	addi r6,r6,-1 // count the parallel vforks in
	61	stwcx. r6,0,r5 // negative cached pid values
	62	bne-- 2b
	63
	64	li r0,SYS_vfork
65	sc
66	b Lbotch // error return
67
68	cmpwi r4,0
69	beq Lparent // parent, since a1 == 0 in parent,
70
71	li r3,0 // child
72	blr
73
74	Lparent: // r3 == child's pid
75	lwarx r6,0,r5 // we're back, decrement vfork count
76	addi r6,r6,1
77	stwcx. r6,0,r5
78	bne-- Lparent
79	blr // return pid
80
81	Lbotch:
82	lwarx r6,0,r5 // never went, decrement vfork count
83	addi r6,r6,1
84	stwcx. r6,0,r5
85	bne-- Lbotch
86
87	MI_BRANCH_EXTERNAL(cerror)
88
89	#elif defined(__i386__)
90
91	#if defined(__DYNAMIC__)
92	#define GET_CURRENT_PID PICIFY(__current_pid)
93
94	NON_LAZY_STUB(__current_pid)
95	#define __current_pid (%edx)
96	#else
97	#define GET_CURRENT_PID
98	#endif
99
100	/*
101	* If __current_pid >= 0, we want to put a -1 in there
102	* otherwise we just decrement it
103	*/
104
105	LEAF(___vfork, 0)
106	GET_CURRENT_PID
107	movl __current_pid, %eax
108	0:
109	xorl %ecx, %ecx
110	testl %eax, %eax
111	cmovs %eax, %ecx
112	decl %ecx
113	lock
114	cmpxchgl %ecx, __current_pid
115	jne 0b
116	popl %ecx
117	movl $(SYS_vfork), %eax // code for vfork -> eax
118	UNIX_SYSCALL_TRAP // do the system call
119	jnb L1 // jump if CF==0
120	GET_CURRENT_PID
121	lock
122	incl __current_pid
123	pushl %ecx
124	BRANCH_EXTERN(cerror)
125
126	L1:
127	testl %edx, %edx // CF=OF=0, ZF set if zero result
128	jz L2 // parent, since r1 == 0 in parent, 1 in child
129	xorl %eax, %eax // zero eax
130	jmp *%ecx
131
132	L2:
133	GET_CURRENT_PID
134	lock
135	incl __current_pid
136	jmp *%ecx
137
138	#elif defined(__x86_64__)
139
140	/*
141	* If __current_pid >= 0, we want to put a -1 in there
142	* otherwise we just decrement it
143	*/
144
145	LEAF(___vfork, 0)
146	movq __current_pid@GOTPCREL(%rip), %rax
147	movl (%rax), %eax
148	0:
149	xorl %ecx, %ecx
150	testl %eax, %eax
151	cmovs %eax, %ecx
152	subl $1, %ecx
153	movq __current_pid@GOTPCREL(%rip), %rdx
154	lock
155	cmpxchgl %ecx, (%rdx)
156	jne 0b
157	popq %rdi // return address in %rdi
158	movq $ SYSCALL_CONSTRUCT_UNIX(SYS_vfork), %rax // code for vfork -> rax
159	UNIX_SYSCALL_TRAP // do the system call
160	jnb L1 // jump if CF==0
161	movq __current_pid@GOTPCREL(%rip), %rcx
162	lock
163	addq $1, (%rcx)
164	movq (%rcx), %rdi
165	BRANCH_EXTERN(cerror)
166
167	L1:
168	testl %edx, %edx // CF=OF=0, ZF set if zero result
169	jz L2 // parent, since r1 == 0 in parent, 1 in child
170	xorq %rax, %rax // zero rax
171	jmp *%rdi
172
173	L2:
174	movq __current_pid@GOTPCREL(%rip), %rdx
175	lock
176	addq $1, (%rdx)
177	jmp *%rdi
178
2d21ac55 A	179	#else
	180	#error Unsupported architecture
	181	#endif