/* * Copyright (c) 1999-2004 Apple Computer, Inc. All rights reserved. * * @APPLE_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. 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_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 * */ /* 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. */ #include "SYS.h" 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)