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 ([email protected]) 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(tramp_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 addl $1, (%rcx) 116 movq %rax, %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 addl $1, (%rdx) 129 jmp *%rdi 130 UNWIND_EPILOGUE 131 132#elif defined(__arm__) 133 134#include <arm/arch.h> 135 136 .globl cerror 137 MI_ENTRY_POINT(___vfork) 138 139 MI_GET_ADDRESS(r3, __current_pid) // get address of __current_pid 140#ifdef _ARM_ARCH_6 141L0: 142 ldrex r1, [r3] 143 subs r1, r1, #1 // if __current_pid <= 0, decrement it 144 movpl r1, #-1 // otherwise put -1 in there 145 strex r2, r1, [r3] 146 cmp r2, #0 147 bne L0 148#else 149 mov r2, #0x80000000 // load "looking" value 150L0: 151 swp r1, r2, [r3] // look at the value, lock others out 152 cmp r1, r2 // anyone else trying to look? 153 beq L0 // yes, so wait our turn 154 subs r1, r1, #1 // if __current_pid <= 0, decrement it 155 movpl r1, #-1 // otherwise put -1 in there 156 str r1, [r3] 157#endif 158 159 mov r1, #1 // prime results 160 mov r12, #SYS_vfork 161 swi #SWI_SYSCALL // make the syscall 162 bcs Lbotch // error? 163 cmp r1, #0 // parent (r1=0) or child(r1=1) 164 beq Lparent 165 166 //child here... 167 mov r0, #0 168 bx lr // return 169 170Lbotch: 171 stmfd sp!, {lr} 172 MI_CALL_EXTERNAL(_cerror) // jump here on error 173 mov r0,#-1 // set the error 174 // reload values clobbered by cerror (so we can treat them as live in Lparent) 175 MI_GET_ADDRESS(r3, __current_pid) // get address of __current_pid 176 ldmfd sp!, {lr} 177#ifndef _ARM_ARCH_6 178 mov r2, #0x80000000 // load "looking" value 179#endif 180 // fall thru 181 182Lparent: 183#ifdef _ARM_ARCH_6 184 ldrex r1, [r3] 185 add r1, r1, #1 // we're back, decrement vfork count 186 strex r2, r1, [r3] 187 cmp r2, #0 188 bne Lparent 189#else 190 swp r1, r2, [r3] // look at the value, lock others out 191 cmp r1, r2 // anyone else trying to look? 192 beq Lparent // yes, so wait our turn 193 add r1, r1, #1 // we're back, decrement vfork count 194 str r1, [r3] 195#endif 196 197 bx lr // return 198 199#elif defined(__arm64__) 200 201 MI_ENTRY_POINT(___vfork) 202 ARM64_STACK_PROLOG 203 204 MI_GET_ADDRESS(x9, __current_pid) 205Ltry_set_vfork: 206 ldxr w10, [x9] // Get old current pid value (exclusive) 207 mov w11, #-1 // Will be -1 if current value is positive 208 subs w10, w10, #1 // Subtract one 209 csel w12, w11, w10, pl // If >= 0, set to -1, else set to (current - 1) 210 stxr w13, w12, [x9] // Attempt exclusive store to current pid 211 cbnz w13, Ltry_set_vfork // If store failed, retry 212 213 // ARM sets r1 to 1 here. I don't see why. 214 mov w16, #SYS_vfork // Set syscall code 215 svc #SWI_SYSCALL 216 b.cs Lbotch 217 cbz w1, Lparent 218 219 // Child 220 mov w0, #0 221 ARM64_STACK_EPILOG 222 223 // Error case 224Lbotch: 225 PUSH_FRAME 226 bl _cerror // Update errno 227 mov w0, #-1 // Set return value 228 MI_GET_ADDRESS(x9, __current_pid) // Reload current pid address 229 POP_FRAME 230 // Fall through 231Lparent: 232 ldxr w10, [x9] // Exclusive load current pid value 233 add w10, w10, #1 // Increment (i.e. decrement vfork count) 234 stxr w11, w10, [x9] // Attempt exclusive store of updated vfork count 235 cbnz w11, Lparent // If exclusive store failed, retry 236 ARM64_STACK_EPILOG // Done, return 237 238#else 239#error Unsupported architecture 240#endif 241